diff --git a/ethclient/ethclient.go b/ethclient/ethclient.go
index b23e9baa3..4daebda92 100644
--- a/ethclient/ethclient.go
+++ b/ethclient/ethclient.go
@@ -81,6 +81,8 @@ func (ec *Client) getBlock(ctx context.Context, method string, args ...interface
 	err := ec.c.CallContext(ctx, &raw, method, args...)
 	if err != nil {
 		return nil, err
+	} else if len(raw) == 0 {
+		return nil, ethereum.NotFound
 	}
 	// Decode header and transactions.
 	var head *types.Header
@@ -135,6 +137,9 @@ func (ec *Client) getBlock(ctx context.Context, method string, args ...interface
 func (ec *Client) HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error) {
 	var head *types.Header
 	err := ec.c.CallContext(ctx, &head, "eth_getBlockByHash", hash, false)
+	if err == nil && head == nil {
+		err = ethereum.NotFound
+	}
 	return head, err
 }
 
@@ -143,19 +148,31 @@ func (ec *Client) HeaderByHash(ctx context.Context, hash common.Hash) (*types.He
 func (ec *Client) HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error) {
 	var head *types.Header
 	err := ec.c.CallContext(ctx, &head, "eth_getBlockByNumber", toBlockNumArg(number), false)
+	if err == nil && head == nil {
+		err = ethereum.NotFound
+	}
 	return head, err
 }
 
 // TransactionByHash returns the transaction with the given hash.
-func (ec *Client) TransactionByHash(ctx context.Context, hash common.Hash) (*types.Transaction, error) {
-	var tx *types.Transaction
-	err := ec.c.CallContext(ctx, &tx, "eth_getTransactionByHash", hash)
-	if err == nil {
-		if _, r, _ := tx.RawSignatureValues(); r == nil {
-			return nil, fmt.Errorf("server returned transaction without signature")
-		}
+func (ec *Client) TransactionByHash(ctx context.Context, hash common.Hash) (tx *types.Transaction, isPending bool, err error) {
+	var raw json.RawMessage
+	err = ec.c.CallContext(ctx, &raw, "eth_getTransactionByHash", hash)
+	if err != nil {
+		return nil, false, err
+	} else if len(raw) == 0 {
+		return nil, false, ethereum.NotFound
 	}
-	return tx, err
+	if err := json.Unmarshal(raw, tx); err != nil {
+		return nil, false, err
+	} else if _, r, _ := tx.RawSignatureValues(); r == nil {
+		return nil, false, fmt.Errorf("server returned transaction without signature")
+	}
+	var block struct{ BlockHash *common.Hash }
+	if err := json.Unmarshal(raw, &block); err != nil {
+		return nil, false, err
+	}
+	return tx, block.BlockHash == nil, nil
 }
 
 // TransactionCount returns the total number of transactions in the given block.
@@ -170,11 +187,9 @@ func (ec *Client) TransactionInBlock(ctx context.Context, blockHash common.Hash,
 	var tx *types.Transaction
 	err := ec.c.CallContext(ctx, &tx, "eth_getTransactionByBlockHashAndIndex", blockHash, index)
 	if err == nil {
-		var signer types.Signer = types.HomesteadSigner{}
-		if tx.Protected() {
-			signer = types.NewEIP155Signer(tx.ChainId())
-		}
-		if _, r, _ := types.SignatureValues(signer, tx); r == nil {
+		if tx == nil {
+			return nil, ethereum.NotFound
+		} else if _, r, _ := tx.RawSignatureValues(); r == nil {
 			return nil, fmt.Errorf("server returned transaction without signature")
 		}
 	}
@@ -186,8 +201,12 @@ func (ec *Client) TransactionInBlock(ctx context.Context, blockHash common.Hash,
 func (ec *Client) TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error) {
 	var r *types.Receipt
 	err := ec.c.CallContext(ctx, &r, "eth_getTransactionReceipt", txHash)
-	if err == nil && r != nil && len(r.PostState) == 0 {
-		return nil, fmt.Errorf("server returned receipt without post state")
+	if err == nil {
+		if r == nil {
+			return nil, ethereum.NotFound
+		} else if len(r.PostState) == 0 {
+			return nil, fmt.Errorf("server returned receipt without post state")
+		}
 	}
 	return r, err
 }
diff --git a/ethclient/ethclient_test.go b/ethclient/ethclient_test.go
index 102c0d3b2..178eb2be9 100644
--- a/ethclient/ethclient_test.go
+++ b/ethclient/ethclient_test.go
@@ -21,9 +21,9 @@ import "github.com/ethereum/go-ethereum"
 // Verify that Client implements the ethereum interfaces.
 var (
 	_ = ethereum.ChainReader(&Client{})
+	_ = ethereum.TransactionReader(&Client{})
 	_ = ethereum.ChainStateReader(&Client{})
 	_ = ethereum.ChainSyncReader(&Client{})
-	_ = ethereum.ChainHeadEventer(&Client{})
 	_ = ethereum.ContractCaller(&Client{})
 	_ = ethereum.GasEstimator(&Client{})
 	_ = ethereum.GasPricer(&Client{})
diff --git a/interfaces.go b/interfaces.go
index aab0e2029..5e38a9054 100644
--- a/interfaces.go
+++ b/interfaces.go
@@ -18,6 +18,7 @@
 package ethereum
 
 import (
+	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -26,6 +27,9 @@ import (
 	"golang.org/x/net/context"
 )
 
+// NotFound is returned by API methods if the requested item does not exist.
+var NotFound = errors.New("not found")
+
 // TODO: move subscription to package event
 
 // Subscription represents an event subscription where events are
@@ -46,6 +50,8 @@ type Subscription interface {
 // blockchain fork that was previously downloaded and processed by the node. The block
 // number argument can be nil to select the latest canonical block. Reading block headers
 // should be preferred over full blocks whenever possible.
+//
+// The returned error is NotFound if the requested item does not exist.
 type ChainReader interface {
 	BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error)
 	BlockByNumber(ctx context.Context, number *big.Int) (*types.Block, error)
@@ -53,7 +59,30 @@ type ChainReader interface {
 	HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error)
 	TransactionCount(ctx context.Context, blockHash common.Hash) (uint, error)
 	TransactionInBlock(ctx context.Context, blockHash common.Hash, index uint) (*types.Transaction, error)
-	TransactionByHash(ctx context.Context, txHash common.Hash) (*types.Transaction, error)
+
+	// This method subscribes to notifications about changes of the head block of
+	// the canonical chain.
+	SubscribeNewHead(ctx context.Context, ch chan<- *types.Header) (Subscription, error)
+}
+
+// TransactionReader provides access to past transactions and their receipts.
+// Implementations may impose arbitrary restrictions on the transactions and receipts that
+// can be retrieved. Historic transactions may not be available.
+//
+// Avoid relying on this interface if possible. Contract logs (through the LogFilterer
+// interface) are more reliable and usually safer in the presence of chain
+// reorganisations.
+//
+// The returned error is NotFound if the requested item does not exist.
+type TransactionReader interface {
+	// TransactionByHash checks the pool of pending transactions in addition to the
+	// blockchain. The isPending return value indicates whether the transaction has been
+	// mined yet. Note that the transaction may not be part of the canonical chain even if
+	// it's not pending.
+	TransactionByHash(ctx context.Context, txHash common.Hash) (tx *types.Transaction, isPending bool, err error)
+	// TransactionReceipt returns the receipt of a mined transaction. Note that the
+	// transaction may not be included in the current canonical chain even if a receipt
+	// exists.
 	TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error)
 }
 
@@ -83,11 +112,6 @@ type ChainSyncReader interface {
 	SyncProgress(ctx context.Context) (*SyncProgress, error)
 }
 
-// A ChainHeadEventer returns notifications whenever the canonical head block is updated.
-type ChainHeadEventer interface {
-	SubscribeNewHead(ctx context.Context, ch chan<- *types.Header) (Subscription, error)
-}
-
 // CallMsg contains parameters for contract calls.
 type CallMsg struct {
 	From     common.Address  // the sender of the 'transaction'
diff --git a/mobile/ethclient.go b/mobile/ethclient.go
index 668d65e32..a60fc2fa5 100644
--- a/mobile/ethclient.go
+++ b/mobile/ethclient.go
@@ -73,7 +73,8 @@ func (ec *EthereumClient) GetHeaderByNumber(ctx *Context, number int64) (*Header
 
 // GetTransactionByHash returns the transaction with the given hash.
 func (ec *EthereumClient) GetTransactionByHash(ctx *Context, hash *Hash) (*Transaction, error) {
-	tx, err := ec.client.TransactionByHash(ctx.context, hash.hash)
+	// TODO(karalabe): handle isPending
+	tx, _, err := ec.client.TransactionByHash(ctx.context, hash.hash)
 	return &Transaction{tx}, err
 }