diff --git a/blockchain.go b/blockchain.go
index e00fb40..842905a 100644
--- a/blockchain.go
+++ b/blockchain.go
@@ -12,7 +12,7 @@ import (
 	"github.com/boltdb/bolt"
 )
 
-const dbFile = "blockchain.db"
+const dbFile = "blockchain_%s.db"
 const blocksBucket = "blocks"
 const genesisCoinbaseData = "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"
 
@@ -23,8 +23,9 @@ type Blockchain struct {
 }
 
 // CreateBlockchain creates a new blockchain DB
-func CreateBlockchain(address string) *Blockchain {
-	if dbExists() {
+func CreateBlockchain(address, nodeID string) *Blockchain {
+	dbFile := fmt.Sprintf(dbFile, nodeID)
+	if dbExists(dbFile) {
 		fmt.Println("Blockchain already exists.")
 		os.Exit(1)
 	}
@@ -68,8 +69,9 @@ func CreateBlockchain(address string) *Blockchain {
 }
 
 // NewBlockchain creates a new Blockchain with genesis Block
-func NewBlockchain() *Blockchain {
-	if dbExists() == false {
+func NewBlockchain(nodeID string) *Blockchain {
+	dbFile := fmt.Sprintf(dbFile, nodeID)
+	if dbExists(dbFile) == false {
 		fmt.Println("No existing blockchain found. Create one first.")
 		os.Exit(1)
 	}
@@ -246,7 +248,7 @@ func (bc *Blockchain) VerifyTransaction(tx *Transaction) bool {
 	return tx.Verify(prevTXs)
 }
 
-func dbExists() bool {
+func dbExists(dbFile string) bool {
 	if _, err := os.Stat(dbFile); os.IsNotExist(err) {
 		return false
 	}
diff --git a/cli.go b/cli.go
index df4af02..7441e3e 100644
--- a/cli.go
+++ b/cli.go
@@ -4,6 +4,7 @@ import (
 	"flag"
 	"fmt"
 	"log"
+
 	"os"
 )
 
@@ -33,6 +34,12 @@ func (cli *CLI) validateArgs() {
 func (cli *CLI) Run() {
 	cli.validateArgs()
 
+	nodeID := os.Getenv("NODE_ID")
+	if nodeID == "" {
+		fmt.Printf("NODE_ID env. var is not set!")
+		os.Exit(1)
+	}
+
 	getBalanceCmd := flag.NewFlagSet("getbalance", flag.ExitOnError)
 	createBlockchainCmd := flag.NewFlagSet("createblockchain", flag.ExitOnError)
 	createWalletCmd := flag.NewFlagSet("createwallet", flag.ExitOnError)
@@ -99,7 +106,7 @@ func (cli *CLI) Run() {
 			getBalanceCmd.Usage()
 			os.Exit(1)
 		}
-		cli.getBalance(*getBalanceAddress)
+		cli.getBalance(*getBalanceAddress, nodeID)
 	}
 
 	if createBlockchainCmd.Parsed() {
@@ -107,7 +114,7 @@ func (cli *CLI) Run() {
 			createBlockchainCmd.Usage()
 			os.Exit(1)
 		}
-		cli.createBlockchain(*createBlockchainAddress)
+		cli.createBlockchain(*createBlockchainAddress, nodeID)
 	}
 
 	if createWalletCmd.Parsed() {
@@ -119,11 +126,11 @@ func (cli *CLI) Run() {
 	}
 
 	if printChainCmd.Parsed() {
-		cli.printChain()
+		cli.printChain(nodeID)
 	}
 
 	if reindexUTXOCmd.Parsed() {
-		cli.reindexUTXO()
+		cli.reindexUTXO(nodeID)
 	}
 
 	if sendCmd.Parsed() {
@@ -132,7 +139,7 @@ func (cli *CLI) Run() {
 			os.Exit(1)
 		}
 
-		cli.send(*sendFrom, *sendTo, *sendAmount)
+		cli.send(*sendFrom, *sendTo, *sendAmount, nodeID)
 	}
 
 	if startNodeCmd.Parsed() {
diff --git a/cli_createblockchain.go b/cli_createblockchain.go
index 358e88b..7e69405 100644
--- a/cli_createblockchain.go
+++ b/cli_createblockchain.go
@@ -5,11 +5,11 @@ import (
 	"log"
 )
 
-func (cli *CLI) createBlockchain(address string) {
+func (cli *CLI) createBlockchain(address, nodeID string) {
 	if !ValidateAddress(address) {
 		log.Panic("ERROR: Address is not valid")
 	}
-	bc := CreateBlockchain(address)
+	bc := CreateBlockchain(address, nodeID)
 	defer bc.db.Close()
 
 	UTXOSet := UTXOSet{bc}
diff --git a/cli_getbalance.go b/cli_getbalance.go
index 814569d..a86e3dc 100644
--- a/cli_getbalance.go
+++ b/cli_getbalance.go
@@ -5,11 +5,11 @@ import (
 	"log"
 )
 
-func (cli *CLI) getBalance(address string) {
+func (cli *CLI) getBalance(address, nodeID string) {
 	if !ValidateAddress(address) {
 		log.Panic("ERROR: Address is not valid")
 	}
-	bc := NewBlockchain()
+	bc := NewBlockchain(nodeID)
 	UTXOSet := UTXOSet{bc}
 	defer bc.db.Close()
 
diff --git a/cli_printchain.go b/cli_printchain.go
index 8541d2f..ba22cf5 100644
--- a/cli_printchain.go
+++ b/cli_printchain.go
@@ -5,8 +5,8 @@ import (
 	"strconv"
 )
 
-func (cli *CLI) printChain() {
-	bc := NewBlockchain()
+func (cli *CLI) printChain(nodeID string) {
+	bc := NewBlockchain(nodeID)
 	defer bc.db.Close()
 
 	bci := bc.Iterator()
diff --git a/cli_reindexutxo.go b/cli_reindexutxo.go
index 74d3b03..87db324 100644
--- a/cli_reindexutxo.go
+++ b/cli_reindexutxo.go
@@ -2,8 +2,8 @@ package main
 
 import "fmt"
 
-func (cli *CLI) reindexUTXO() {
-	bc := NewBlockchain()
+func (cli *CLI) reindexUTXO(nodeID string) {
+	bc := NewBlockchain(nodeID)
 	UTXOSet := UTXOSet{bc}
 	UTXOSet.Reindex()
 
diff --git a/cli_send.go b/cli_send.go
index 456c264..a7c6f72 100644
--- a/cli_send.go
+++ b/cli_send.go
@@ -5,7 +5,7 @@ import (
 	"log"
 )
 
-func (cli *CLI) send(from, to string, amount int) {
+func (cli *CLI) send(from, to string, amount int, nodeID string) {
 	if !ValidateAddress(from) {
 		log.Panic("ERROR: Sender address is not valid")
 	}
@@ -13,7 +13,7 @@ func (cli *CLI) send(from, to string, amount int) {
 		log.Panic("ERROR: Recipient address is not valid")
 	}
 
-	bc := NewBlockchain()
+	bc := NewBlockchain(nodeID)
 	UTXOSet := UTXOSet{bc}
 	defer bc.db.Close()
 
diff --git a/server.go b/server.go
index ba0906d..37a87ac 100644
--- a/server.go
+++ b/server.go
@@ -126,7 +126,7 @@ func handleVersion(request []byte) {
 	knownNodes = append(knownNodes, payload.AddrFrom)
 }
 
-func handleConnection(conn net.Conn) {
+func handleConnection(conn net.Conn, bc *Blockchain) {
 	request, err := ioutil.ReadAll(conn)
 	if err != nil {
 		log.Panic(err)
@@ -161,12 +161,14 @@ func StartServer(nodeID string) {
 		sendVersion(fmt.Sprintf("localhost:%s", dnsNodeID))
 	}
 
+	bc := NewBlockchain(nodeID)
+
 	for {
 		conn, err := ln.Accept()
 		if err != nil {
 			log.Panic(err)
 		}
-		go handleConnection(conn)
+		go handleConnection(conn, bc)
 	}
 }