diff --git a/bchain/mempool.go b/bchain/mempool.go
index 558a514c..9aa4cd79 100644
--- a/bchain/mempool.go
+++ b/bchain/mempool.go
@@ -8,12 +8,28 @@ import (
 	"github.com/golang/glog"
 )
 
+type scriptIndex struct {
+	script string
+	n      uint32
+}
+
+type outpoint struct {
+	txid string
+	vout uint32
+}
+
+type inputOutput struct {
+	outputScripts []scriptIndex
+	inputs        []outpoint
+}
+
 // Mempool is mempool handle.
 type Mempool struct {
-	chain      *BitcoinRPC
-	mux        sync.Mutex
-	scriptToTx map[string][]string
-	txToScript map[string][]string
+	chain           *BitcoinRPC
+	mux             sync.Mutex
+	txToInputOutput map[string]inputOutput
+	scriptToTx      map[string][]outpoint
+	inputs          map[outpoint]string
 }
 
 // NewMempool creates new mempool handler.
@@ -26,14 +42,30 @@ func (m *Mempool) GetTransactions(outputScript []byte) ([]string, error) {
 	m.mux.Lock()
 	defer m.mux.Unlock()
 	scriptHex := hex.EncodeToString(outputScript)
-	return m.scriptToTx[scriptHex], nil
+	outpoints := m.scriptToTx[scriptHex]
+	txs := make([]string, 0, len(outpoints)+len(outpoints)/2)
+	for _, o := range outpoints {
+		txs = append(txs, o.txid)
+		i := m.inputs[o]
+		if i != "" {
+			txs = append(txs, i)
+		}
+	}
+	return txs, nil
 }
 
-func (m *Mempool) updateMaps(newScriptToTx map[string][]string, newTxToScript map[string][]string) {
+// GetInput returns transaction which spends given outpoint
+func (m *Mempool) GetInput(outputTxid string, vout uint32) string {
+	o := outpoint{txid: outputTxid, vout: vout}
+	return m.inputs[o]
+}
+
+func (m *Mempool) updateMappings(newTxToInputOutput map[string]inputOutput, newScriptToTx map[string][]outpoint, newInputs map[outpoint]string) {
 	m.mux.Lock()
 	defer m.mux.Unlock()
+	m.txToInputOutput = newTxToInputOutput
 	m.scriptToTx = newScriptToTx
-	m.txToScript = newTxToScript
+	m.inputs = newInputs
 }
 
 // Resync gets mempool transactions and maps output scripts to transactions.
@@ -46,30 +78,41 @@ func (m *Mempool) Resync() error {
 	if err != nil {
 		return err
 	}
-	newScriptToTx := make(map[string][]string)
-	newTxToScript := make(map[string][]string)
+	newTxToInputOutput := make(map[string]inputOutput, len(m.txToInputOutput)+1)
+	newScriptToTx := make(map[string][]outpoint, len(m.scriptToTx)+1)
+	newInputs := make(map[outpoint]string, len(m.inputs)+1)
 	for _, txid := range txs {
-		scripts := m.txToScript[txid]
-		if scripts == nil {
+		io, exists := m.txToInputOutput[txid]
+		if !exists {
 			tx, err := m.chain.GetTransaction(txid)
 			if err != nil {
 				glog.Error("cannot get transaction ", txid, ": ", err)
 				continue
 			}
-			scripts = make([]string, 0, len(tx.Vout))
+			io.outputScripts = make([]scriptIndex, 0, len(tx.Vout))
 			for _, output := range tx.Vout {
 				outputScript := output.ScriptPubKey.Hex
 				if outputScript != "" {
-					scripts = append(scripts, outputScript)
+					io.outputScripts = append(io.outputScripts, scriptIndex{outputScript, output.N})
 				}
 			}
+			io.inputs = make([]outpoint, 0, len(tx.Vin))
+			for _, input := range tx.Vin {
+				if input.Coinbase != "" {
+					continue
+				}
+				io.inputs = append(io.inputs, outpoint{input.Txid, input.Vout})
+			}
 		}
-		newTxToScript[txid] = scripts
-		for _, script := range scripts {
-			newScriptToTx[script] = append(newScriptToTx[script], txid)
+		newTxToInputOutput[txid] = io
+		for _, si := range io.outputScripts {
+			newScriptToTx[si.script] = append(newScriptToTx[si.script], outpoint{txid, si.n})
+		}
+		for _, i := range io.inputs {
+			newInputs[i] = txid
 		}
 	}
-	m.updateMaps(newScriptToTx, newTxToScript)
-	glog.Info("Mempool: resync finished in ", time.Since(start), ", ", len(m.txToScript), " transactions in mempool")
+	m.updateMappings(newTxToInputOutput, newScriptToTx, newInputs)
+	glog.Info("Mempool: resync finished in ", time.Since(start), ", ", len(m.txToInputOutput), " transactions in mempool")
 	return nil
 }