diff --git a/src/main/scala/org/scalacoin/script/interpreter/ScriptInterpreter.scala b/src/main/scala/org/scalacoin/script/interpreter/ScriptInterpreter.scala
index b8e7f40451..dd903b9fd5 100644
--- a/src/main/scala/org/scalacoin/script/interpreter/ScriptInterpreter.scala
+++ b/src/main/scala/org/scalacoin/script/interpreter/ScriptInterpreter.scala
@@ -2,6 +2,7 @@ package org.scalacoin.script.interpreter
 
 import org.scalacoin.protocol.script.{ScriptSignature, ScriptPubKey}
 import org.scalacoin.protocol.transaction.Transaction
+import org.scalacoin.script.locktime.{OP_CHECKLOCKTIMEVERIFY, LockTimeInterpreter}
 import org.scalacoin.script.splice.{SpliceInterpreter, OP_SIZE}
 import org.scalacoin.script.{ScriptProgramImpl, ScriptProgram}
 import org.scalacoin.script.arithmetic._
@@ -19,7 +20,8 @@ import scala.annotation.tailrec
  * Created by chris on 1/6/16.
  */
 trait ScriptInterpreter extends CryptoInterpreter with StackInterpreter with ControlOperationsInterpreter
-  with BitwiseInterpreter with ConstantInterpreter with ArithmeticInterpreter with SpliceInterpreter {
+  with BitwiseInterpreter with ConstantInterpreter with ArithmeticInterpreter with SpliceInterpreter
+  with LockTimeInterpreter {
 
   private def logger = LoggerFactory.getLogger(this.getClass().toString)
 
@@ -132,6 +134,10 @@ trait ScriptInterpreter extends CryptoInterpreter with StackInterpreter with Con
 
         //splice operations
         case OP_SIZE :: t => loop(opSize(program))
+
+        //locktime operations
+        case OP_CHECKLOCKTIMEVERIFY :: t => loop(opCheckLockTimeVerify(program))
+
         //no more script operations to run, True is represented by any representation of non-zero
         case Nil => program.stack.headOption != Some(ScriptFalse)
         case h :: t => throw new RuntimeException(h + " was unmatched")
diff --git a/src/main/scala/org/scalacoin/script/locktime/LockTimeInterpreter.scala b/src/main/scala/org/scalacoin/script/locktime/LockTimeInterpreter.scala
new file mode 100644
index 0000000000..880183e9a0
--- /dev/null
+++ b/src/main/scala/org/scalacoin/script/locktime/LockTimeInterpreter.scala
@@ -0,0 +1,41 @@
+package org.scalacoin.script.locktime
+
+import org.scalacoin.script.constant.{ScriptNumberImpl, ScriptNumber}
+import org.scalacoin.script.{ScriptProgramImpl, ScriptProgram}
+
+/**
+ * Created by chris on 2/8/16.
+ */
+trait LockTimeInterpreter {
+
+
+  /**
+   * Marks transaction as invalid if the top stack item is greater than the transaction's nLockTime field,
+   * otherwise script evaluation continues as though an OP_NOP was executed. Transaction is also invalid if
+   * 1. the stack is empty; or
+   * 2. the top stack item is negative; or
+   * 3. the top stack item is greater than or equal to 500000000 while the transaction's nLockTime field is less than 500000000,
+   * or vice versa; or
+   * 4. the input's nSequence field is equal to 0xffffffff.
+   * The precise semantics are described in BIP 0065
+   * @param program
+   * @return
+   */
+  def opCheckLockTimeVerify(program : ScriptProgram) : ScriptProgram = {
+    require(program.script.headOption.isDefined && program.script.head == OP_CHECKLOCKTIMEVERIFY,
+      "Script top must be OP_CHECKLOCKTIMEVERIFY")
+    if (program.stack.size == 0) {
+      ScriptProgramImpl(program.stack, program.script.tail, program.transaction, program.altStack,false)
+    } else {
+      val isValid = program.stack.head match {
+        case s : ScriptNumber if (s < ScriptNumberImpl(0)) => false
+        case s : ScriptNumber if (s > ScriptNumberImpl(500000000) && program.transaction.lockTime < 500000000) => false
+        case s : ScriptNumber if (s < ScriptNumberImpl(500000000) && program.transaction.lockTime > 500000000) => false
+        case s if (program.transaction.inputs.map(_.sequence == 0xffffffff).exists(_ == true)) => false
+        case _ => true
+      }
+      ScriptProgramImpl(program.stack, program.script.tail, program.transaction, program.altStack,isValid)
+    }
+  }
+
+}