Index: src/script/interpreter.cpp
===================================================================
--- src/script/interpreter.cpp
+++ src/script/interpreter.cpp
@@ -337,8 +337,8 @@
 
             if (opcode == OP_CAT || opcode == OP_SUBSTR || opcode == OP_LEFT ||
                 opcode == OP_RIGHT || opcode == OP_INVERT || opcode == OP_2MUL ||
-                opcode == OP_2DIV || opcode == OP_MUL || opcode == OP_MOD ||
-                opcode == OP_LSHIFT || opcode == OP_RSHIFT) {
+                opcode == OP_2DIV || opcode == OP_MUL || opcode == OP_LSHIFT ||
+                opcode == OP_RSHIFT) {
                 // Disabled opcodes.
                 return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE);
             }
@@ -894,6 +894,7 @@
                     case OP_ADD:
                     case OP_SUB:
                     case OP_DIV:
+                    case OP_MOD:
                     case OP_BOOLAND:
                     case OP_BOOLOR:
                     case OP_NUMEQUAL:
@@ -931,6 +932,14 @@
                                 }
                                 bn = bn1 / bn2;
                                 break;
+                            case OP_MOD:
+                                // 2nd operand must not be 0
+                                if (bn2 == 0) {
+                                    return set_error(
+                                        serror, SCRIPT_ERR_MOD_BY_ZERO);
+                                }
+                                bn = bn1 % bn2;
+                                break;
 
                             case OP_BOOLAND:
                                 bn = (bn1 != bnZero && bn2 != bnZero);
Index: src/script/script.h
===================================================================
--- src/script/script.h
+++ src/script/script.h
@@ -279,6 +279,12 @@
     inline CScriptNum operator/(const CScriptNum &rhs) const {
         return operator/(rhs.m_value);
     }
+    inline CScriptNum operator%(const int64_t &rhs) const {
+        return CScriptNum(m_value % rhs);
+    }
+    inline CScriptNum operator%(const CScriptNum &rhs) const {
+        return operator%(rhs.m_value);
+    }
 
     inline CScriptNum &operator+=(const CScriptNum &rhs) {
         return operator+=(rhs.m_value);
Index: src/script/script_error.h
===================================================================
--- src/script/script_error.h
+++ src/script/script_error.h
@@ -35,6 +35,7 @@
     SCRIPT_ERR_UNBALANCED_CONDITIONAL,
     SCRIPT_ERR_INVALID_BITWISE_OPERATION,
     SCRIPT_ERR_DIV_BY_ZERO,
+    SCRIPT_ERR_MOD_BY_ZERO,
 
     /* CHECKLOCKTIMEVERIFY and CHECKSEQUENCEVERIFY */
     SCRIPT_ERR_NEGATIVE_LOCKTIME,
Index: src/script/script_error.cpp
===================================================================
--- src/script/script_error.cpp
+++ src/script/script_error.cpp
@@ -50,6 +50,8 @@
             return "Invalid bitwise operation (check length of inputs)";
         case SCRIPT_ERR_DIV_BY_ZERO:
             return "Invalid division operation";
+        case SCRIPT_ERR_MOD_BY_ZERO:
+            return "Invalid modulo operation";
         case SCRIPT_ERR_NEGATIVE_LOCKTIME:
             return "Negative locktime";
         case SCRIPT_ERR_UNSATISFIED_LOCKTIME:
Index: src/test/data/script_tests.json
===================================================================
--- src/test/data/script_tests.json
+++ src/test/data/script_tests.json
@@ -826,7 +826,6 @@
 ["2 0 IF 2MUL ELSE 1 ENDIF", "NOP", "P2SH,STRICTENC", "DISABLED_OPCODE", "2MUL disabled"],
 ["2 0 IF 2DIV ELSE 1 ENDIF", "NOP", "P2SH,STRICTENC", "DISABLED_OPCODE", "2DIV disabled"],
 ["2 2 0 IF MUL ELSE 1 ENDIF", "NOP", "P2SH,STRICTENC", "DISABLED_OPCODE", "MUL disabled"],
-["2 2 0 IF MOD ELSE 1 ENDIF", "NOP", "P2SH,STRICTENC", "DISABLED_OPCODE", "MOD disabled"],
 ["2 2 0 IF LSHIFT ELSE 1 ENDIF", "NOP", "P2SH,STRICTENC", "DISABLED_OPCODE", "LSHIFT disabled"],
 ["2 2 0 IF RSHIFT ELSE 1 ENDIF", "NOP", "P2SH,STRICTENC", "DISABLED_OPCODE", "RSHIFT disabled"],
 
@@ -844,7 +843,6 @@
 ["2 DUP MUL", "4 EQUAL", "P2SH,STRICTENC", "DISABLED_OPCODE", "disabled"],
 ["2 2MUL", "4 EQUAL", "P2SH,STRICTENC", "DISABLED_OPCODE", "disabled"],
 ["2 2DIV", "1 EQUAL", "P2SH,STRICTENC", "DISABLED_OPCODE", "disabled"],
-["7 3 MOD", "1 EQUAL", "P2SH,STRICTENC", "DISABLED_OPCODE", "disabled"],
 ["2 2 LSHIFT", "8 EQUAL", "P2SH,STRICTENC", "DISABLED_OPCODE", "disabled"],
 ["2 1 RSHIFT", "1 EQUAL", "P2SH,STRICTENC", "DISABLED_OPCODE", "disabled"],
 
Index: src/test/op_code.cpp
===================================================================
--- src/test/op_code.cpp
+++ src/test/op_code.cpp
@@ -272,6 +272,38 @@
         test(script,stack_t{{0xc0,0xe1,0xe4,0x80},{0x84}},flags,stack_t{{0x70,0x38,0x39}});
     }
 
+    /// OP_MOD tests
+
+    void test_mod(uint32_t flags) {
+        CScript script;
+        script << OP_MOD;
+
+        test(script,stack_t(),flags,SCRIPT_ERR_INVALID_STACK_OPERATION);
+        test(script,stack_t{{}},flags,SCRIPT_ERR_INVALID_STACK_OPERATION);
+
+        //test not valid numbers
+        test(script,stack_t{{0x01,0x02,0x03,0x04,0x05},{0x01,0x02,0x03,0x04,0x05}},flags,SCRIPT_ERR_UNKNOWN_ERROR);
+        test(script,stack_t{{0x01,0x02,0x03,0x04,0x05},{0x01}},flags,SCRIPT_ERR_UNKNOWN_ERROR);
+        test(script,stack_t{{0x01,0x05},{0x01,0x02,0x03,0x04,0x05}},flags,SCRIPT_ERR_UNKNOWN_ERROR);
+
+        //mod by 0
+        test(script,stack_t{{0x01,0x05},{}},flags,SCRIPT_ERR_MOD_BY_ZERO);
+
+        //56488123%321 =148
+        //56488123%3 =1
+        //56488123%564881230 =56488123
+        test(script,stack_t{{0xbb,0xf0,0x5d,0x03},{0x41,0x01}},flags,stack_t{{0x94,0x00}});
+        test(script,stack_t{{0xbb,0xf0,0x5d,0x03},{0x03}},flags,stack_t{{0x01}});
+        test(script,stack_t{{0xbb,0xf0,0x5d,0x03},{0x4e,0x67,0xab,0x21}},flags,stack_t{{0xbb,0xf0,0x5d,0x03}});
+
+        //-56488123%321 = -148
+        //-56488123%3 = -1
+        //-56488123%564881230 = -56488123
+        test(script,stack_t{{0xbb,0xf0,0x5d,0x83},{0x41,0x01}},flags,stack_t{{0x94,0x80}});
+        test(script,stack_t{{0xbb,0xf0,0x5d,0x83},{0x03}},flags,stack_t{{0x81}});
+        test(script,stack_t{{0xbb,0xf0,0x5d,0x83},{0x4e,0x67,0xab,0x21}},flags,stack_t{{0xbb,0xf0,0x5d,0x83}});
+    }
+
 }
 
 /// Entry points
@@ -306,5 +338,12 @@
     test_div(STANDARD_LOCKTIME_VERIFY_FLAGS);
 }
 
+BOOST_AUTO_TEST_CASE(op_mod) {
+    test_mod(0);
+    test_mod(STANDARD_SCRIPT_VERIFY_FLAGS);
+    test_mod(STANDARD_NOT_MANDATORY_VERIFY_FLAGS);
+    test_mod(STANDARD_LOCKTIME_VERIFY_FLAGS);
+}
+
 BOOST_AUTO_TEST_SUITE_END()