diff --git a/GeneralStateTests/stExample/balance.json b/GeneralStateTests/stExample/balance.json
new file mode 100644
index 00000000000..9e2cb3b175f
--- /dev/null
+++ b/GeneralStateTests/stExample/balance.json
@@ -0,0 +1,75 @@
+{
+    "balance" : {
+        "_info" : {
+            "comment" : "A test for balance opcode result",
+            "filling-rpc-server" : "Geth-1.9.2-unstable",
+            "filling-tool-version" : "retesteth-0.0.1+commit.3eec1785.Linux.g++",
+            "lllcversion" : "Version: 0.5.0-develop.2019.8.22+commit.9709dfe0.Linux.g++",
+            "source" : "src/GeneralStateTestsFiller/stExample/balanceFiller.json",
+            "sourceHash" : "9141384ee241bb46f746fa6b05b159e3c6343e3e458d821f9c2d1099e8e2935a"
+        },
+        "env" : {
+            "currentCoinbase" : "0x2adc25665018aa1fe0e6bc666dac8fc2697ff9ba",
+            "currentDifficulty" : "0x020000",
+            "currentGasLimit" : "0x0f4240",
+            "currentNumber" : "0x01",
+            "currentTimestamp" : "0x03e8",
+            "previousHash" : "0x5e20a0453cecd065ea59c37ac63e079ee08998b6045136a8ce6635c7912ec0b6"
+        },
+        "post" : {
+            "ConstantinopleFix" : [
+                {
+                    "indexes" : {
+                        "data" : 0,
+                        "gas" : 0,
+                        "value" : 0
+                    },
+                    "hash" : "0xab994f2aec0b19c80b5ae8bd380aaea9c51f5dec81efc8fc9882dfc6f3b91ccb",
+                    "logs" : "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347"
+                }
+            ],
+            "Istanbul" : [
+                {
+                    "indexes" : {
+                        "data" : 0,
+                        "gas" : 0,
+                        "value" : 0
+                    },
+                    "hash" : "0xab994f2aec0b19c80b5ae8bd380aaea9c51f5dec81efc8fc9882dfc6f3b91ccb",
+                    "logs" : "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347"
+                }
+            ]
+        },
+        "pre" : {
+            "0x095e7baea6a6c7c4c2dfeb977efac326af552d87" : {
+                "balance" : "0x0de0b6b3a7640000",
+                "code" : "0x73a94f5374fce5edbc8e2a8697c15331677e6ebf0b316000555a600155",
+                "nonce" : "0x00",
+                "storage" : {
+                }
+            },
+            "0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b" : {
+                "balance" : "0x0de0b6b3a7640000",
+                "code" : "0x",
+                "nonce" : "0x00",
+                "storage" : {
+                }
+            }
+        },
+        "transaction" : {
+            "data" : [
+                "0x"
+            ],
+            "gasLimit" : [
+                "0x061a80"
+            ],
+            "gasPrice" : "0x01",
+            "nonce" : "0x00",
+            "secretKey" : "0x45a915e4d060149eb4365960e6a7a45f334393093061116b197e3240065ff2d8",
+            "to" : "0x095e7baea6a6c7c4c2dfeb977efac326af552d87",
+            "value" : [
+                "0x0186a0"
+            ]
+        }
+    }
+}
\ No newline at end of file
diff --git a/Retesteth/default/config b/Retesteth/default/config
index b9b1d3a2785..f204351f5fb 100644
--- a/Retesteth/default/config
+++ b/Retesteth/default/config
@@ -18,6 +18,7 @@
                 "EIP158",
                 "Byzantium",
                 "Constantinople",
-                "ConstantinopleFix"
+                "ConstantinopleFix",
+                "Istanbul"
         ]
 }
diff --git a/Retesteth/default/genesis/Istanbul.json b/Retesteth/default/genesis/Istanbul.json
new file mode 100644
index 00000000000..8b92df92562
--- /dev/null
+++ b/Retesteth/default/genesis/Istanbul.json
@@ -0,0 +1,77 @@
+{
+    "params" : {
+        "homesteadForkBlock" : "0x00",
+        "EIP150ForkBlock" : "0x00",
+        "EIP158ForkBlock" : "0x00",
+        "byzantiumForkBlock" : "0x00",
+        "constantinopleForkBlock" : "0x00",
+        "constantinopleFixForkBlock" : "0x00",
+        "istanbulForkBlock" : "0x00"
+    },
+    "accounts" : {
+        "0x0000000000000000000000000000000000000001" : {
+            "precompiled" : {
+                "name" : "ecrecover",
+                "linear" : {
+                    "base" : 3000,
+                    "word" : 0
+                }
+            }
+        },
+        "0x0000000000000000000000000000000000000002" : {
+            "precompiled" : {
+                "name" : "sha256",
+                "linear" : {
+                    "base" : 60,
+                    "word" : 12
+                }
+            }
+        },
+        "0x0000000000000000000000000000000000000003" : {
+            "precompiled" : {
+                "name" : "sha256",
+                "linear" : {
+                    "base" : 600,
+                    "word" : 120
+                }
+            }
+        },
+        "0x0000000000000000000000000000000000000004" : {
+            "precompiled" : {
+                "name" : "identity",
+                "linear" : {
+                    "base" : 15,
+                    "word" : 3
+                }
+            }
+        },
+        "0x0000000000000000000000000000000000000005" : {
+            "precompiled" : {
+                "name" : "modexp"
+            }
+        },
+        "0x0000000000000000000000000000000000000006" : {
+            "precompiled" : {
+                "name" : "alt_bn128_G1_add",
+                "linear" : {
+                    "base" : 500,
+                    "word" : 0
+                }
+            }
+        },
+        "0x0000000000000000000000000000000000000007" : {
+            "precompiled" : {
+                "name" : "alt_bn128_G1_mul",
+                "linear" : {
+                    "base" : 40000,
+                    "word" : 0
+                }
+            }
+        },
+        "0x0000000000000000000000000000000000000008" : {
+            "precompiled" : {
+                "name" : "alt_bn128_pairing_product"
+            }
+        }
+    }
+}
diff --git a/src/GeneralStateTestsFiller/stExample/balanceFiller.json b/src/GeneralStateTestsFiller/stExample/balanceFiller.json
new file mode 100644
index 00000000000..be2187d90a6
--- /dev/null
+++ b/src/GeneralStateTestsFiller/stExample/balanceFiller.json
@@ -0,0 +1,93 @@
+{
+    "balance" : {
+        "_info" : {
+            "comment" : "A test for balance opcode result"
+        },
+        "env" : {
+            "//comment" : "A blockinfo section (obsolite). Do not change. (only coinbase and gasLimit could be changed)",
+            "currentCoinbase" : "2adc25665018aa1fe0e6bc666dac8fc2697ff9ba",
+            "currentDifficulty" : "0x20000",
+            "currentGasLimit" : "1000000",
+            "currentNumber" : "1",
+            "currentTimestamp" : "1000",
+            "previousHash" : "5e20a0453cecd065ea59c37ac63e079ee08998b6045136a8ce6635c7912ec0b6"
+        },
+        "//comment" : "Expect section is the post condition for the transaction result",
+        "expect" : [
+            {
+                "//comment" : "indexes are used to specify post condition for a given transaction range.",
+                "//comment" : "transaction section describe multiple transaction which will be executed on pre state",
+                "indexes" : {
+                    "//comment" : "-1 for transaction with any data from this field. or a particular index, or range [0, 1, 2]",
+                    "data" : -1,
+                    "gas" : 0,
+                    "value" : -1
+                },
+                "//comment" : "hard fork order: Frontier, Homestead, EIP150, EIP155, Byzantium, Constantinople, ConstantinopleFix",
+                "network" : [">=ConstantinopleFix"],
+                "result" : {
+                    "//comment" : "Account in expect section would be checked for the fields specified here (balance, code, storage)",
+                    "095e7baea6a6c7c4c2dfeb977efac326af552d87" : {
+                        "//comment" : "Better not to check the gas or mining reward affected account's balances.",
+                        "//comment" : "A change in gasPrice will affect the test and this post condition.",
+                        "//comment" : "So unless the test doesn't really requrie it, don't check coinbase/miner address balance or sender balance in post section",
+                        "balance" : "1000000000000100000",
+                        "//comment" : "Byte Code example",
+                        "code" : "0x73a94f5374fce5edbc8e2a8697c15331677e6ebf0b316000555a600155",
+                        "storage" : {
+                            "0x00" : "0x0de0b6b3a75c5ee0",
+                            "0x01" : "0x0578c0"
+                        }
+                    }
+                }
+            }
+        ],
+        "//comment" : "Pre condition state for the test",
+        "pre" : {
+            "095e7baea6a6c7c4c2dfeb977efac326af552d87" : {
+                "balance" : "1000000000000000000",
+                "//comment": "If lllc compiler is installed, LLL code will be converted into EVM bytecode when --filltests",
+                "//code" : "put result of add(1,1) into storage cell 0",
+                "//comment" : "Bytecode example: ",
+                "code" : "0x6001600101600055",
+                "//comment" : "LLL Code example. Use LLL with comments, so your tests would have transparent source logic.",
+                "//comment" : "If the LLL is to bit for .json use .yml test format for better sourcing of the contract",
+                "//code" : "{ [[0]] (BALANCE 0xa94f5374fce5edbc8e2a8697c15331677e6ebf0b) [[1]] (GAS) }",
+                "code" : "0x73a94f5374fce5edbc8e2a8697c15331677e6ebf0b316000555a600155",
+                "nonce" : "0",
+                "storage" : {
+                }
+            },
+            "//comment" : "A pre state account description must be complete (balance, code, nonce, storage)",
+            "a94f5374fce5edbc8e2a8697c15331677e6ebf0b" : {
+                "balance" : "1000000000000000000",
+                "code" : "0x",
+                "nonce" : "0",
+                "storage" : {
+                }
+            }
+        },
+        "//comment" : "multiple transaction description that will be applied on a pre state",
+        "transaction" : {
+            "//comment" : "foreach d in `data` { foreach g in `gasLimit` { foreach v in `value`  {  pre.applyTransaction(d, g, v)  }}}",
+            "//comment" : "each element of the data array is treated same as account's code field. You could use LLL here",
+            "data" : [
+                ""
+            ],
+            "//comment" : "Be careful when adding gasLimits that are < then intrinsic gas cost. StateTests are not allowed to have invalid transactions",
+            "gasLimit" : [
+                "400000"
+            ],
+            "gasPrice" : "1",
+            "//comment" : "nonce must be same as account nonce a94f5374fce5edbc8e2a8697c15331677e6ebf0b",
+            "nonce" : "0",
+            "//comment" : "secretKey is a privKey of a94f5374fce5edbc8e2a8697c15331677e6ebf0b",
+            "secretKey" : "45a915e4d060149eb4365960e6a7a45f334393093061116b197e3240065ff2d8",
+            "//comment" : "if `to` field is empty, the transaction becomes contract creation. code from data will be executed as a deployment code",
+            "to" : "095e7baea6a6c7c4c2dfeb977efac326af552d87",
+            "value" : [
+                "100000"
+            ]
+        }
+    }
+}