diff --git a/accept.go b/accept.go
index 5e66436f..8908aa8f 100644
--- a/accept.go
+++ b/accept.go
@@ -60,16 +60,10 @@ func (b *BlockChain) maybeAcceptBlock(block *btcutil.Block) error {
 	}
 
 	// Ensure all transactions in the block are finalized.
-	for i, tx := range block.MsgBlock().Transactions {
+	for _, tx := range block.Transactions() {
 		if !IsFinalizedTransaction(tx, blockHeight, blockHeader.Timestamp) {
-			// Use the TxSha function from the block rather
-			// than the transaction itself since the block version
-			// is cached.  Also, it's safe to ignore the error here
-			// since the only reason TxSha can fail is if the index
-			// is out of range which is impossible here.
-			txSha, _ := block.TxSha(i)
 			str := fmt.Sprintf("block contains unfinalized "+
-				"transaction %v", txSha)
+				"transaction %v", tx.Sha())
 			return RuleError(str)
 		}
 	}
@@ -129,7 +123,7 @@ func (b *BlockChain) maybeAcceptBlock(block *btcutil.Block) error {
 			if prevNode != nil {
 				expectedHeight = prevNode.height + 1
 			}
-			coinbaseTx := block.MsgBlock().Transactions[0]
+			coinbaseTx := block.Transactions()[0]
 			err := checkSerializedHeight(coinbaseTx, expectedHeight)
 			if err != nil {
 				return err
diff --git a/checkpoints.go b/checkpoints.go
index 4f4c4019..a0b3ff84 100644
--- a/checkpoints.go
+++ b/checkpoints.go
@@ -154,11 +154,11 @@ func (b *BlockChain) findLatestKnownCheckpoint() (*btcutil.Block, error) {
 
 // isNonstandardTransaction determines whether a transaction contains any
 // scripts which are not one of the standard types.
-func isNonstandardTransaction(tx *btcwire.MsgTx) bool {
+func isNonstandardTransaction(tx *btcutil.Tx) bool {
 	// TODO(davec): Should there be checks for the input signature scripts?
 
 	// Check all of the output public key scripts for non-standard scripts.
-	for _, txOut := range tx.TxOut {
+	for _, txOut := range tx.MsgTx().TxOut {
 		scriptClass := btcscript.GetScriptClass(txOut.PkScript)
 		if scriptClass == btcscript.NonStandardTy {
 			return true
@@ -235,7 +235,7 @@ func (b *BlockChain) IsCheckpointCandidate(block *btcutil.Block) (bool, error) {
 
 	// A checkpoint must have transactions that only contain standard
 	// scripts.
-	for _, tx := range block.MsgBlock().Transactions {
+	for _, tx := range block.Transactions() {
 		if isNonstandardTransaction(tx) {
 			return false, nil
 		}
diff --git a/internal_test.go b/internal_test.go
index b919d543..282804f9 100644
--- a/internal_test.go
+++ b/internal_test.go
@@ -13,7 +13,6 @@ package btcchain
 
 import (
 	"github.com/conformal/btcutil"
-	"github.com/conformal/btcwire"
 	"time"
 )
 
@@ -37,6 +36,6 @@ func TstTimeSorter(times []time.Time) timeSorter {
 
 // TstCheckSerializedHeight makes the internal checkSerializedHeight function
 // available to the test package.
-func TstCheckSerializedHeight(coinbaseTx *btcwire.MsgTx, wantHeight int64) error {
+func TstCheckSerializedHeight(coinbaseTx *btcutil.Tx, wantHeight int64) error {
 	return checkSerializedHeight(coinbaseTx, wantHeight)
 }
diff --git a/merkle.go b/merkle.go
index e0aa0053..b0e2f1d7 100644
--- a/merkle.go
+++ b/merkle.go
@@ -69,21 +69,15 @@ func hashMerkleBranches(left *btcwire.ShaHash, right *btcwire.ShaHash) *btcwire.
 // Since this function uses nodes that are pointers to the hashes, empty nodes
 // will be nil.
 func BuildMerkleTreeStore(block *btcutil.Block) []*btcwire.ShaHash {
-	numTransactions := len(block.MsgBlock().Transactions)
-
 	// Calculate how many entries are required to hold the binary merkle
 	// tree as a linear array and create an array of that size.
-	nextPoT := nextPowerOfTwo(numTransactions)
+	nextPoT := nextPowerOfTwo(len(block.Transactions()))
 	arraySize := nextPoT*2 - 1
 	merkles := make([]*btcwire.ShaHash, arraySize)
 
 	// Create the base transaction shas and populate the array with them.
-	for i := 0; i < numTransactions; i++ {
-		// Ignore the error since the only reason TxSha can fail is
-		// if the index is out of range which is impossible here due
-		// to using a loop over the existing transactions.
-		sha, _ := block.TxSha(i)
-		merkles[i] = sha
+	for i, tx := range block.Transactions() {
+		merkles[i] = tx.Sha()
 	}
 
 	// Start the array offset after the last transaction and adjusted to the
diff --git a/scriptval.go b/scriptval.go
index 8426e14f..64e51be4 100644
--- a/scriptval.go
+++ b/scriptval.go
@@ -19,16 +19,10 @@ type txValidate struct {
 	err     error
 }
 
-// txProcessList
-type txProcessList struct {
-	txsha btcwire.ShaHash
-	tx    *btcwire.MsgTx
-}
-
 // validateTxIn validates a the script pair for the passed spending transaction
 // (along with the specific input index) and origin transaction (with the
 // specific output index).
-func validateTxIn(txInIdx int, txin *btcwire.TxIn, txSha *btcwire.ShaHash, tx *btcwire.MsgTx, originTx *btcwire.MsgTx, flags btcscript.ScriptFlags) error {
+func validateTxIn(txInIdx int, txin *btcwire.TxIn, tx *btcutil.Tx, originTx *btcutil.Tx, flags btcscript.ScriptFlags) error {
 	// If the input transaction has no previous input, there is nothing
 	// to check.
 	originTxIdx := txin.PreviousOutpoint.Index
@@ -36,17 +30,17 @@ func validateTxIn(txInIdx int, txin *btcwire.TxIn, txSha *btcwire.ShaHash, tx *b
 		return nil
 	}
 
-	if originTxIdx >= uint32(len(originTx.TxOut)) {
+	if originTxIdx >= uint32(len(originTx.MsgTx().TxOut)) {
 		originTxSha := &txin.PreviousOutpoint.Hash
 		log.Warnf("unable to locate source tx %v spending tx %v",
-			originTxSha, &txSha)
+			originTxSha, tx.Sha())
 		return fmt.Errorf("invalid index %x", originTxIdx)
 	}
 
 	sigScript := txin.SignatureScript
-	pkScript := originTx.TxOut[originTxIdx].PkScript
-	engine, err := btcscript.NewScript(sigScript, pkScript, txInIdx, tx,
-		flags)
+	pkScript := originTx.MsgTx().TxOut[originTxIdx].PkScript
+	engine, err := btcscript.NewScript(sigScript, pkScript, txInIdx,
+		tx.MsgTx(), flags)
 	if err != nil {
 		return err
 	}
@@ -62,9 +56,9 @@ func validateTxIn(txInIdx int, txin *btcwire.TxIn, txSha *btcwire.ShaHash, tx *b
 
 // ValidateTransactionScripts validates the scripts for the passed transaction
 // using multiple goroutines.
-func ValidateTransactionScripts(tx *btcwire.MsgTx, txHash *btcwire.ShaHash, txStore TxStore, flags btcscript.ScriptFlags) (err error) {
+func ValidateTransactionScripts(tx *btcutil.Tx, txStore TxStore, flags btcscript.ScriptFlags) (err error) {
 	c := make(chan txValidate)
-	job := tx.TxIn
+	job := tx.MsgTx().TxIn
 	resultErrors := make([]error, len(job))
 
 	var currentItem int
@@ -72,12 +66,12 @@ func ValidateTransactionScripts(tx *btcwire.MsgTx, txHash *btcwire.ShaHash, txSt
 
 	processFunc := func(txInIdx int) {
 		log.Tracef("validating tx %v input %v len %v",
-			txHash, currentItem, len(job))
+			tx.Sha(), currentItem, len(job))
 		txin := job[txInIdx]
 		originTxSha := &txin.PreviousOutpoint.Hash
 		origintxidx := txin.PreviousOutpoint.Index
 
-		var originTx *btcwire.MsgTx
+		var originTx *btcutil.Tx
 		if origintxidx != math.MaxUint32 {
 			txInfo, ok := txStore[*originTxSha]
 			if !ok {
@@ -87,8 +81,7 @@ func ValidateTransactionScripts(tx *btcwire.MsgTx, txHash *btcwire.ShaHash, txSt
 			}
 			originTx = txInfo.Tx
 		}
-		err := validateTxIn(txInIdx, job[txInIdx], txHash, tx, originTx,
-			flags)
+		err := validateTxIn(txInIdx, txin, tx, originTx, flags)
 		r := txValidate{txInIdx, err}
 		c <- r
 	}
@@ -114,7 +107,8 @@ func ValidateTransactionScripts(tx *btcwire.MsgTx, txHash *btcwire.ShaHash, txSt
 	}
 	for i := 0; i < len(job); i++ {
 		if resultErrors[i] != nil {
-			log.Warnf("tx %v failed input %v, err %v", txHash, i, resultErrors[i])
+			log.Warnf("tx %v failed input %v, err %v", tx.Sha(), i,
+				resultErrors[i])
 		}
 	}
 	return
@@ -130,17 +124,14 @@ func checkBlockScripts(block *btcutil.Block, txStore TxStore) error {
 		flags |= btcscript.ScriptBip16
 	}
 
-	txList := block.MsgBlock().Transactions
+	txList := block.Transactions()
 	c := make(chan txValidate)
 	resultErrors := make([]error, len(txList))
 
 	var currentItem int
 	var completedItems int
 	processFunc := func(txIdx int) {
-		tx := txList[txIdx]
-		txHash, _ := block.TxSha(txIdx)
-
-		err := ValidateTransactionScripts(tx, txHash, txStore, flags)
+		err := ValidateTransactionScripts(txList[txIdx], txStore, flags)
 		r := txValidate{txIdx, err}
 		c <- r
 	}
diff --git a/txlookup.go b/txlookup.go
index 193f5331..3d5c1df2 100644
--- a/txlookup.go
+++ b/txlookup.go
@@ -14,7 +14,7 @@ import (
 // TxData contains contextual information about transactions such as which block
 // they were found in and whether or not the outputs are spent.
 type TxData struct {
-	Tx          *btcwire.MsgTx
+	Tx          *btcutil.Tx
 	Hash        *btcwire.ShaHash
 	BlockHeight int64
 	Spent       []bool
@@ -33,23 +33,19 @@ type TxStore map[btcwire.ShaHash]*TxData
 func connectTransactions(txStore TxStore, block *btcutil.Block) error {
 	// Loop through all of the transactions in the block to see if any of
 	// them are ones we need to update and spend based on the results map.
-	for i, tx := range block.MsgBlock().Transactions {
-		txHash, err := block.TxSha(i)
-		if err != nil {
-			return err
-		}
-
+	for _, tx := range block.Transactions() {
 		// Update the transaction store with the transaction information
 		// if it's one of the requested transactions.
-		if txD, exists := txStore[*txHash]; exists {
+		msgTx := tx.MsgTx()
+		if txD, exists := txStore[*tx.Sha()]; exists {
 			txD.Tx = tx
 			txD.BlockHeight = block.Height()
-			txD.Spent = make([]bool, len(tx.TxOut))
+			txD.Spent = make([]bool, len(msgTx.TxOut))
 			txD.Err = nil
 		}
 
 		// Spend the origin transaction output.
-		for _, txIn := range tx.TxIn {
+		for _, txIn := range msgTx.TxIn {
 			originHash := &txIn.PreviousOutpoint.Hash
 			originIndex := txIn.PreviousOutpoint.Index
 			if originTx, exists := txStore[*originHash]; exists {
@@ -67,18 +63,13 @@ func connectTransactions(txStore TxStore, block *btcutil.Block) error {
 func disconnectTransactions(txStore TxStore, block *btcutil.Block) error {
 	// Loop through all of the transactions in the block to see if any of
 	// them are ones that need to be undone based on the transaction store.
-	for i, tx := range block.MsgBlock().Transactions {
-		txHash, err := block.TxSha(i)
-		if err != nil {
-			return err
-		}
-
+	for _, tx := range block.Transactions() {
 		// Clear this transaction from the transaction store if needed.
 		// Only clear it rather than deleting it because the transaction
 		// connect code relies on its presence to decide whether or not
 		// to update the store and any transactions which exist on both
 		// sides of a fork would otherwise not be updated.
-		if txD, exists := txStore[*txHash]; exists {
+		if txD, exists := txStore[*tx.Sha()]; exists {
 			txD.Tx = nil
 			txD.BlockHeight = 0
 			txD.Spent = nil
@@ -86,7 +77,7 @@ func disconnectTransactions(txStore TxStore, block *btcutil.Block) error {
 		}
 
 		// Unspend the origin transaction output.
-		for _, txIn := range tx.TxIn {
+		for _, txIn := range tx.MsgTx().TxIn {
 			originHash := &txIn.PreviousOutpoint.Hash
 			originIndex := txIn.PreviousOutpoint.Index
 			originTx, exists := txStore[*originHash]
@@ -146,7 +137,7 @@ func fetchTxStoreMain(db btcdb.Db, txSet map[btcwire.ShaHash]bool, includeSpent
 		// cause subtle errors, so avoid the potential altogether.
 		txD.Err = txReply.Err
 		if txReply.Err == nil {
-			txD.Tx = txReply.Tx
+			txD.Tx = btcutil.NewTx(txReply.Tx)
 			txD.BlockHeight = txReply.Height
 			txD.Spent = make([]bool, len(txReply.TxSpent))
 			copy(txD.Spent, txReply.TxSpent)
@@ -240,14 +231,9 @@ func (b *BlockChain) fetchInputTransactions(node *blockNode, block *btcutil.Bloc
 	// this block could be referencing other transactions earlier in this
 	// block which are not yet in the chain.
 	txInFlight := map[btcwire.ShaHash]int{}
-	transactions := block.MsgBlock().Transactions
-	for i := range transactions {
-		// Get transaction hash.  It's safe to ignore the error since
-		// it's already cached in the nominal code path and the only
-		// way it can fail is if the index is out of range which is
-		// impossible here.
-		txHash, _ := block.TxSha(i)
-		txInFlight[*txHash] = i
+	transactions := block.Transactions()
+	for i, tx := range transactions {
+		txInFlight[*tx.Sha()] = i
 	}
 
 	// Loop through all of the transaction inputs (except for the coinbase
@@ -256,7 +242,7 @@ func (b *BlockChain) fetchInputTransactions(node *blockNode, block *btcutil.Bloc
 	txNeededSet := make(map[btcwire.ShaHash]bool)
 	txStore := make(TxStore)
 	for i, tx := range transactions[1:] {
-		for _, txIn := range tx.TxIn {
+		for _, txIn := range tx.MsgTx().TxIn {
 			// Add an entry to the transaction store for the needed
 			// transaction with it set to missing by default.
 			originHash := &txIn.PreviousOutpoint.Hash
@@ -279,7 +265,7 @@ func (b *BlockChain) fetchInputTransactions(node *blockNode, block *btcutil.Bloc
 				originTx := transactions[inFlightIndex]
 				txD.Tx = originTx
 				txD.BlockHeight = node.height
-				txD.Spent = make([]bool, len(originTx.TxOut))
+				txD.Spent = make([]bool, len(originTx.MsgTx().TxOut))
 				txD.Err = nil
 			} else {
 				txNeededSet[*originHash] = true
@@ -306,18 +292,13 @@ func (b *BlockChain) fetchInputTransactions(node *blockNode, block *btcutil.Bloc
 // passed transaction from the point of view of the end of the main chain.  It
 // also attempts to fetch the transaction itself so the returned TxStore can be
 // examined for duplicate transactions.
-func (b *BlockChain) FetchTransactionStore(tx *btcwire.MsgTx) (TxStore, error) {
-	txHash, err := tx.TxSha()
-	if err != nil {
-		return nil, err
-	}
-
+func (b *BlockChain) FetchTransactionStore(tx *btcutil.Tx) (TxStore, error) {
 	// Create a set of needed transactions from the transactions referenced
 	// by the inputs of the passed transaction.  Also, add the passed
 	// transaction itself as a way for the caller to detect duplicates.
 	txNeededSet := make(map[btcwire.ShaHash]bool)
-	txNeededSet[txHash] = true
-	for _, txIn := range tx.TxIn {
+	txNeededSet[*tx.Sha()] = true
+	for _, txIn := range tx.MsgTx().TxIn {
 		txNeededSet[txIn.PreviousOutpoint.Hash] = true
 	}
 
diff --git a/validate.go b/validate.go
index 00ed8ff2..88b677fd 100644
--- a/validate.go
+++ b/validate.go
@@ -94,7 +94,9 @@ func isNullOutpoint(outpoint *btcwire.OutPoint) bool {
 // represented in the block chain by a transaction with a single input that has
 // a previous output transaction index set to the maximum value along with a
 // zero hash.
-func IsCoinBase(msgTx *btcwire.MsgTx) bool {
+func IsCoinBase(tx *btcutil.Tx) bool {
+	msgTx := tx.MsgTx()
+
 	// A coin base must only have one transaction input.
 	if len(msgTx.TxIn) != 1 {
 		return false
@@ -111,7 +113,9 @@ func IsCoinBase(msgTx *btcwire.MsgTx) bool {
 }
 
 // IsFinalizedTransaction determines whether or not a transaction is finalized.
-func IsFinalizedTransaction(msgTx *btcwire.MsgTx, blockHeight int64, blockTime time.Time) bool {
+func IsFinalizedTransaction(tx *btcutil.Tx, blockHeight int64, blockTime time.Time) bool {
+	msgTx := tx.MsgTx()
+
 	// Lock time of zero means the transaction is finalized.
 	lockTime := msgTx.LockTime
 	if lockTime == 0 {
@@ -175,14 +179,15 @@ func calcBlockSubsidy(height int64) int64 {
 
 // CheckTransactionSanity performs some preliminary checks on a transaction to
 // ensure it is sane.  These checks are context free.
-func CheckTransactionSanity(tx *btcwire.MsgTx) error {
+func CheckTransactionSanity(tx *btcutil.Tx) error {
 	// A transaction must have at least one input.
-	if len(tx.TxIn) == 0 {
+	msgTx := tx.MsgTx()
+	if len(msgTx.TxIn) == 0 {
 		return RuleError("transaction has no inputs")
 	}
 
 	// A transaction must have at least one output.
-	if len(tx.TxOut) == 0 {
+	if len(msgTx.TxOut) == 0 {
 		return RuleError("transaction has no outputs")
 	}
 
@@ -198,7 +203,7 @@ func CheckTransactionSanity(tx *btcwire.MsgTx) error {
 	// as a satoshi.  One bitcoin is a quantity of satoshi as defined by the
 	// satoshiPerBitcoin constant.
 	var totalSatoshi int64
-	for _, txOut := range tx.TxOut {
+	for _, txOut := range msgTx.TxOut {
 		satoshi := txOut.Value
 		if satoshi < 0 {
 			str := fmt.Sprintf("transaction output has negative "+
@@ -231,7 +236,7 @@ func CheckTransactionSanity(tx *btcwire.MsgTx) error {
 
 	// Check for duplicate transaction inputs.
 	existingTxOut := make(map[btcwire.OutPoint]bool)
-	for _, txIn := range tx.TxIn {
+	for _, txIn := range msgTx.TxIn {
 		if _, exists := existingTxOut[txIn.PreviousOutpoint]; exists {
 			return RuleError("transaction contains duplicate outpoint")
 		}
@@ -240,7 +245,7 @@ func CheckTransactionSanity(tx *btcwire.MsgTx) error {
 
 	// Coinbase script length must be between min and max length.
 	if IsCoinBase(tx) {
-		slen := len(tx.TxIn[0].SignatureScript)
+		slen := len(msgTx.TxIn[0].SignatureScript)
 		if slen < minCoinbaseScriptLen || slen > maxCoinbaseScriptLen {
 			str := fmt.Sprintf("coinbase transaction script length "+
 				"of %d is out of range (min: %d, max: %d)",
@@ -250,7 +255,7 @@ func CheckTransactionSanity(tx *btcwire.MsgTx) error {
 	} else {
 		// Previous transaction outputs referenced by the inputs to this
 		// transaction must not be null.
-		for _, txIn := range tx.TxIn {
+		for _, txIn := range msgTx.TxIn {
 			prevOut := &txIn.PreviousOutpoint
 			if isNullOutpoint(prevOut) {
 				return RuleError("transaction input refers to " +
@@ -302,7 +307,9 @@ func (b *BlockChain) checkProofOfWork(block *btcutil.Block) error {
 // input and output scripts in the provided transaction.  This uses the
 // quicker, but imprecise, signature operation counting mechanism from
 // btcscript.
-func countSigOps(msgTx *btcwire.MsgTx) int {
+func countSigOps(tx *btcutil.Tx) int {
+	msgTx := tx.MsgTx()
+
 	// Accumulate the number of signature operations in all transaction
 	// inputs.
 	totalSigOps := 0
@@ -325,20 +332,15 @@ func countSigOps(msgTx *btcwire.MsgTx) int {
 // transactions which are of the pay-to-script-hash type.  This uses the
 // precise, signature operation counting mechanism from btcscript which requires
 // access to the input transaction scripts.
-func countP2SHSigOps(msgTx *btcwire.MsgTx, isCoinBaseTx bool, txStore TxStore) (int, error) {
+func countP2SHSigOps(tx *btcutil.Tx, isCoinBaseTx bool, txStore TxStore) (int, error) {
 	// Coinbase transactions have no interesting inputs.
 	if isCoinBaseTx {
 		return 0, nil
 	}
 
-	// TODO(davec): Need to pass the cached version in.
-	txHash, err := msgTx.TxSha()
-	if err != nil {
-		return 0, err
-	}
-
 	// Accumulate the number of signature operations in all transaction
 	// inputs.
+	msgTx := tx.MsgTx()
 	totalSigOps := 0
 	for _, txIn := range msgTx.TxIn {
 		// Ensure the referenced input transaction is available.
@@ -347,23 +349,24 @@ func countP2SHSigOps(msgTx *btcwire.MsgTx, isCoinBaseTx bool, txStore TxStore) (
 		if !exists || originTx.Err != nil || originTx.Tx == nil {
 			str := fmt.Sprintf("unable to find input transaction "+
 				"%v referenced from transaction %v", txInHash,
-				txHash)
+				tx.Sha())
 			return 0, RuleError(str)
 		}
+		originMsgTx := originTx.Tx.MsgTx()
 
 		// Ensure the output index in the referenced transaction is
 		// available.
 		originTxIndex := txIn.PreviousOutpoint.Index
-		if originTxIndex >= uint32(len(originTx.Tx.TxOut)) {
+		if originTxIndex >= uint32(len(originMsgTx.TxOut)) {
 			str := fmt.Sprintf("out of bounds input index %d in "+
 				"transaction %v referenced from transaction %v",
-				originTxIndex, txInHash, txHash)
+				originTxIndex, txInHash, tx.Sha())
 			return 0, RuleError(str)
 		}
 
 		// We're only interested in pay-to-script-hash types, so skip
 		// this input if it's not one.
-		pkScript := originTx.Tx.TxOut[originTxIndex].PkScript
+		pkScript := originMsgTx.TxOut[originTxIndex].PkScript
 		if !btcscript.IsPayToScriptHash(pkScript) {
 			continue
 		}
@@ -407,8 +410,7 @@ func (b *BlockChain) checkBlockSanity(block *btcutil.Block) error {
 	}
 
 	// Ensure the block time is not more than 2 hours in the future.
-	msgBlock := block.MsgBlock()
-	header := &msgBlock.Header
+	header := &block.MsgBlock().Header
 	if header.Timestamp.After(time.Now().Add(time.Hour * 2)) {
 		str := fmt.Sprintf("block timestamp of %v is too far in the "+
 			"future", header.Timestamp)
@@ -416,7 +418,7 @@ func (b *BlockChain) checkBlockSanity(block *btcutil.Block) error {
 	}
 
 	// A block must have at least one transaction.
-	transactions := msgBlock.Transactions
+	transactions := block.Transactions()
 	if len(transactions) == 0 {
 		return RuleError("block does not contain any transactions")
 	}
@@ -463,11 +465,8 @@ func (b *BlockChain) checkBlockSanity(block *btcutil.Block) error {
 	// since the transaction hashes are already cached due to building the
 	// merkle tree above.
 	existingTxHashes := make(map[btcwire.ShaHash]bool)
-	txShas, err := block.TxShas()
-	if err != nil {
-		return err
-	}
-	for _, hash := range txShas {
+	for _, tx := range transactions {
+		hash := tx.Sha()
 		if _, exists := existingTxHashes[*hash]; exists {
 			str := fmt.Sprintf("block contains duplicate "+
 				"transaction %v", hash)
@@ -497,8 +496,8 @@ func (b *BlockChain) checkBlockSanity(block *btcutil.Block) error {
 
 // checkSerializedHeight checks if the signature script in the passed
 // transaction starts with the serialized block height of wantHeight.
-func checkSerializedHeight(coinbaseTx *btcwire.MsgTx, wantHeight int64) error {
-	sigScript := coinbaseTx.TxIn[0].SignatureScript
+func checkSerializedHeight(coinbaseTx *btcutil.Tx, wantHeight int64) error {
+	sigScript := coinbaseTx.MsgTx().TxIn[0].SignatureScript
 	if len(sigScript) < 1 {
 		str := "the coinbase signature script for blocks of " +
 			"version %d or greater must start with the " +
@@ -601,20 +600,15 @@ func (b *BlockChain) checkBIP0030(node *blockNode, block *btcutil.Block) error {
 // amount, and verifying the signatures to prove the spender was the owner of
 // the bitcoins and therefore allowed to spend them.  As it checks the inputs,
 // it also calculates the total fees for the transaction and returns that value.
-func CheckTransactionInputs(tx *btcwire.MsgTx, txHeight int64, txStore TxStore) (int64, error) {
+func CheckTransactionInputs(tx *btcutil.Tx, txHeight int64, txStore TxStore) (int64, error) {
 	// Coinbase transactions have no inputs.
 	if IsCoinBase(tx) {
 		return 0, nil
 	}
 
-	// TODO(davec): Need to pass the cached version in.
-	txHash, err := tx.TxSha()
-	if err != nil {
-		return 0, err
-	}
-
+	txHash := tx.Sha()
 	var totalSatoshiIn int64
-	for _, txIn := range tx.TxIn {
+	for _, txIn := range tx.MsgTx().TxIn {
 		// Ensure the input is available.
 		txInHash := &txIn.PreviousOutpoint.Hash
 		originTx, exists := txStore[*txInHash]
@@ -659,7 +653,7 @@ func CheckTransactionInputs(tx *btcwire.MsgTx, txHeight int64, txStore TxStore)
 		// a transaction are in a unit value known as a satoshi.  One
 		// bitcoin is a quantity of satoshi as defined by the
 		// satoshiPerBitcoin constant.
-		originTxSatoshi := originTx.Tx.TxOut[originTxIndex].Value
+		originTxSatoshi := originTx.Tx.MsgTx().TxOut[originTxIndex].Value
 		if originTxSatoshi < 0 {
 			str := fmt.Sprintf("transaction output has negative "+
 				"value of %v", originTxSatoshi)
@@ -693,7 +687,7 @@ func CheckTransactionInputs(tx *btcwire.MsgTx, txHeight int64, txStore TxStore)
 	// to ignore overflow and out of range errors here because those error
 	// conditions would have already been caught by checkTransactionSanity.
 	var totalSatoshiOut int64
-	for _, txOut := range tx.TxOut {
+	for _, txOut := range tx.MsgTx().TxOut {
 		totalSatoshiOut += txOut.Value
 	}
 
@@ -771,7 +765,7 @@ func (b *BlockChain) checkConnectBlock(node *blockNode, block *btcutil.Block) er
 	// expands the count to include a precise count of pay-to-script-hash
 	// signature operations in each of the input transaction public key
 	// scripts.
-	transactions := block.MsgBlock().Transactions
+	transactions := block.Transactions()
 	totalSigOps := 0
 	for i, tx := range transactions {
 		numsigOps := countSigOps(tx)
@@ -832,7 +826,7 @@ func (b *BlockChain) checkConnectBlock(node *blockNode, block *btcutil.Block) er
 	// errors here because those error conditions would have already been
 	// caught by checkTransactionSanity.
 	var totalSatoshiOut int64
-	for _, txOut := range transactions[0].TxOut {
+	for _, txOut := range transactions[0].MsgTx().TxOut {
 		totalSatoshiOut += txOut.Value
 	}
 	expectedSatoshiOut := calcBlockSubsidy(node.height) + totalFees
diff --git a/validate_test.go b/validate_test.go
index 5cde8f1a..004c490b 100644
--- a/validate_test.go
+++ b/validate_test.go
@@ -66,8 +66,9 @@ func TestCheckSerializedHeight(t *testing.T) {
 
 	t.Logf("Running %d tests", len(tests))
 	for i, test := range tests {
-		tx := coinbaseTx.Copy()
-		tx.TxIn[0].SignatureScript = test.sigScript
+		msgTx := coinbaseTx.Copy()
+		msgTx.TxIn[0].SignatureScript = test.sigScript
+		tx := btcutil.NewTx(msgTx)
 
 		err := btcchain.TstCheckSerializedHeight(tx, test.wantHeight)
 		if reflect.TypeOf(err) != reflect.TypeOf(test.err) {