diff --git a/actors/evm/src/interpreter/execution.rs b/actors/evm/src/interpreter/execution.rs
index 5fcc105fc..22f013b8d 100644
--- a/actors/evm/src/interpreter/execution.rs
+++ b/actors/evm/src/interpreter/execution.rs
@@ -163,6 +163,7 @@ pub mod opcodes {
         0x59: MSIZE,
         0x5a: GAS,
         0x5b: JUMPDEST,
+        0x5e: MCOPY,
         0x5F: PUSH0,
         0x60: PUSH1,
         0x61: PUSH2,
diff --git a/actors/evm/src/interpreter/instructions/memory.rs b/actors/evm/src/interpreter/instructions/memory.rs
index 8e410fe27..ba9e532ce 100644
--- a/actors/evm/src/interpreter/instructions/memory.rs
+++ b/actors/evm/src/interpreter/instructions/memory.rs
@@ -53,6 +53,48 @@ pub fn get_memory_region(
     }))
 }
 
+#[inline]
+pub fn mcopy(
+    state: &mut ExecutionState,
+    _: &System<impl Runtime>,
+    dest_index: U256,
+    src_index: U256,
+    size: U256,
+) -> Result<(), ActorError> {
+    // Copy memory from src_index to dest_index.
+    // Handles overlapping slices as if using an intermediate buffer, ensuring correct copying.
+    // Expands memory if src_index + size or dest_index + size exceeds current bounds.
+    // Returns an error if memory regions are invalid or cannot be allocated.
+
+    if size > 0 {
+        copy_within_memory(&mut state.memory, dest_index, src_index, size)
+    } else {
+        Ok(())
+    }
+}
+
+pub fn copy_within_memory(
+    memory: &mut Memory,
+    dest_index: U256,
+    src_index: U256,
+    size: U256,
+) -> Result<(), ActorError> {
+    // Expand memory to accommodate requested src_index + size
+    let src_region = get_memory_region(memory, src_index, size)?.expect("empty region");
+
+    // Expand memory to match dest_index + size
+    let destination_region = get_memory_region(memory, dest_index, size)?.expect("empty region");
+
+    // Named variables for clarity
+    let source_range = src_region.offset..(src_region.offset + src_region.size.get());
+    let destination_index = destination_region.offset;
+
+    // Copy memory
+    memory.copy_within(source_range, destination_index);
+
+    Ok(())
+}
+
 pub fn copy_to_memory(
     memory: &mut Memory,
     dest_offset: U256,
@@ -200,6 +242,247 @@ mod tests {
         assert_eq!(&mem[0..4], result_data);
     }
 
+    #[test]
+    fn test_mcopy() {
+        const LENGTH: usize = 2;
+        const OFFSET: usize = 1;
+        const DEST_OFFSET: usize = 0;
+
+        evm_unit_test! {
+            (m) {
+                MCOPY;
+            }
+
+            // Grow memory and set initial values
+            m.state.memory.grow(32);
+            m.state.memory[..3].copy_from_slice(&[0x00, 0x01, 0x02]);
+
+            // Set up stack
+            m.state.stack.push(U256::from(LENGTH)).unwrap();
+            m.state.stack.push(U256::from(OFFSET)).unwrap();
+            m.state.stack.push(U256::from(DEST_OFFSET)).unwrap();
+
+            // Execute and assert
+            assert!(m.step().is_ok(), "execution step failed");
+            assert_eq!(m.state.stack.len(), 0);
+
+            // Setup expected memory and assert
+            let mut expected = [0u8; 32];
+            expected[..3].copy_from_slice(&[0x01, 0x02, 0x02]);
+            assert_eq!(&*m.state.memory, &expected);
+        };
+    }
+
+    #[test]
+    fn test_mcopy_0_32_32() {
+        evm_unit_test! {
+            (m) {
+                MCOPY;
+            }
+
+            // Grow memory and set initial values
+            m.state.memory.grow(64);
+            m.state.memory[32..64].copy_from_slice(&[
+                0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+                0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f
+            ]);
+
+            // Set up stack
+            m.state.stack.push(U256::from(32)).unwrap();  // length
+            m.state.stack.push(U256::from(32)).unwrap();  // source offset
+            m.state.stack.push(U256::from(0)).unwrap();   // destination offset
+
+            // Execute and assert
+            assert!(m.step().is_ok(), "execution step failed");
+            assert_eq!(m.state.stack.len(), 0);
+
+            // Setup expected memory and assert
+            let mut expected = [0u8; 64];
+            expected[0..64].copy_from_slice(&[
+                0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+                0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+                0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+                0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f
+            ]);
+            assert_eq!(&*m.state.memory, &expected);
+        };
+    }
+
+    #[test]
+    fn test_mcopy_0_0_32() {
+        evm_unit_test! {
+            (m) {
+                MCOPY;
+            }
+
+            // Grow memory and set initial values
+            m.state.memory.grow(32);
+            m.state.memory[..32].copy_from_slice(&[0x01; 32]);
+
+            // Set up stack
+            m.state.stack.push(U256::from(32)).unwrap();  // length
+            m.state.stack.push(U256::from(0)).unwrap();   // source offset
+            m.state.stack.push(U256::from(0)).unwrap();   // destination offset
+
+            // Execute and assert
+            assert!(m.step().is_ok(), "execution step failed");
+            assert_eq!(m.state.stack.len(), 0);
+
+            // Setup expected memory and assert
+            let expected = [0x01; 32];
+            assert_eq!(&m.state.memory[..32], &expected);
+        };
+    }
+
+    #[test]
+    fn test_mcopy_0_1_8() {
+        evm_unit_test! {
+            (m) {
+                MCOPY;
+            }
+
+            // Grow memory and set initial values
+            m.state.memory.grow(32);
+            m.state.memory[..8].copy_from_slice(&[0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07]);
+            m.state.memory[8] = 0x08;
+
+            // Set up stack
+            m.state.stack.push(U256::from(8)).unwrap();   // length
+            m.state.stack.push(U256::from(1)).unwrap();   // source offset
+            m.state.stack.push(U256::from(0)).unwrap();   // destination offset
+
+            // Execute and assert
+            assert!(m.step().is_ok(), "execution step failed");
+            assert_eq!(m.state.stack.len(), 0);
+
+            // Setup expected memory and assert
+            let mut expected = [0u8; 32];
+            expected[..8].copy_from_slice(&[0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08]);
+            expected[8] = 0x08;
+            assert_eq!(&m.state.memory[..9], &expected[..9]);
+        };
+    }
+
+    #[test]
+    fn test_mcopy_1_0_8() {
+        evm_unit_test! {
+            (m) {
+                MCOPY;
+            }
+
+            // Grow memory and set initial values
+            m.state.memory.grow(32);
+            m.state.memory[..8].copy_from_slice(&[0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07]);
+            m.state.memory[8] = 0x08;
+
+            // Set up stack
+            m.state.stack.push(U256::from(8)).unwrap();   // length
+            m.state.stack.push(U256::from(0)).unwrap();   // source offset
+            m.state.stack.push(U256::from(1)).unwrap();   // destination offset
+
+            // Execute and assert
+            assert!(m.step().is_ok(), "execution step failed");
+            assert_eq!(m.state.stack.len(), 0);
+
+            // Setup expected memory and assert
+            let mut expected = [0u8; 32];
+            expected[..8].copy_from_slice(&[0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06]);
+            expected[8] = 0x07;
+            assert_eq!(&m.state.memory[..9], &expected[..9]);
+        };
+    }
+
+    #[test]
+    fn test_mcopy_out_of_range_dest() {
+        evm_unit_test! {
+            (m) {
+                MCOPY;
+            }
+
+            // Initial memory setup
+            m.state.memory.grow(32);
+            m.state.memory[..4].copy_from_slice(&[0x01, 0x02, 0x03, 0x04]);
+
+            // Set up stack: Attempt to copy to a destination beyond the current memory range
+            m.state.stack.push(U256::from(4)).unwrap();  // length
+            m.state.stack.push(U256::from(0)).unwrap();  // source offset
+            m.state.stack.push(U256::from(64)).unwrap(); // out of range destination offset
+
+            // Execute and expect memory expansion
+            assert!(m.step().is_ok(), "execution step failed");
+            assert_eq!(m.state.stack.len(), 0);
+
+            // Check that memory was expanded correctly
+            assert_eq!(m.state.memory.len(), 96);
+
+            // Check the memory contents
+            let mut expected = [0u8; 96];
+            expected[..4].copy_from_slice(&[0x01, 0x02, 0x03, 0x04]);
+            expected[64..68].copy_from_slice(&[0x01, 0x02, 0x03, 0x04]);
+            assert_eq!(&*m.state.memory, &expected[..]);
+        };
+    }
+
+    #[test]
+    fn test_mcopy_partially_out_of_range_source() {
+        evm_unit_test! {
+            (m) {
+                MCOPY;
+            }
+
+            // Initial memory setup
+            m.state.memory.grow(32);
+            m.state.memory[..28].copy_from_slice(&[0x01; 28]);
+
+            // Set up stack: Source partially out of range
+            m.state.stack.push(U256::from(10)).unwrap();  // length
+            m.state.stack.push(U256::from(24)).unwrap(); // source offset (partially out of range)
+            m.state.stack.push(U256::from(0)).unwrap();  // destination offset
+
+            // Execute and expect memory expansion
+            assert!(m.step().is_ok(), "execution step failed");
+            assert_eq!(m.state.stack.len(), 0);
+
+            // Check the length of the memory after the operation
+            assert_eq!(m.state.memory.len(), 32+EVM_WORD_SIZE);  // Memory should remain at 32 bytes after the operation
+
+            // Check that memory was expanded correctly
+            let mut expected = vec![0x01; 4];  // First 4 bytes copied
+            expected.extend_from_slice(&[0x00; 4]);  // Remaining 4 bytes unchanged
+            assert_eq!(&m.state.memory[..8], &expected[..8]);
+        };
+    }
+
+    #[test]
+    fn test_mcopy_fully_out_of_range_dest_fails() {
+        evm_unit_test! {
+            (m) {
+                MCOPY;
+            }
+
+            // Initial memory setup
+            m.state.memory.grow(32);
+            m.state.memory[..4].copy_from_slice(&[0x01, 0x02, 0x03, 0x04]);
+
+            // Set up stack: Attempt to copy to a destination fully out of range
+            m.state.stack.push(U256::from(4)).unwrap();  // length
+            m.state.stack.push(U256::from(0)).unwrap();  // source offset
+            m.state.stack.push(U256::from(128)).unwrap(); // fully out of range destination offset
+
+
+            // Execute and assert memory grows
+            assert!(m.step().is_ok(), "expected step to succeed and grow memory");
+            assert_eq!(m.state.memory.len(), 160);  // Expected memory to grow
+
+            // Check the memory contents
+            let mut expected = [0u8; 132];
+            expected[..4].copy_from_slice(&[0x01, 0x02, 0x03, 0x04]);
+            expected[128..132].copy_from_slice(&[0x01, 0x02, 0x03, 0x04]);
+            assert_eq!(&m.state.memory[0..132], &expected[0..132]);
+
+        };
+    }
+
     #[test]
     fn test_mload_nothing() {
         evm_unit_test! {
diff --git a/actors/evm/src/interpreter/instructions/mod.rs b/actors/evm/src/interpreter/instructions/mod.rs
index 5c95e2fa5..b97b407e1 100644
--- a/actors/evm/src/interpreter/instructions/mod.rs
+++ b/actors/evm/src/interpreter/instructions/mod.rs
@@ -352,6 +352,7 @@ def_stdfun_code! { CODESIZE() => call::codesize }
 def_stdproc_code! { CODECOPY(a, b, c) => call::codecopy }
 def_stdfun! { CREATE(a, b, c) => lifecycle::create }
 def_stdfun! { CREATE2(a, b, c, d) => lifecycle::create2 }
+def_stdproc! { MCOPY(a,b,c) => memory::mcopy }
 def_stdproc! { JUMPDEST() => control::nop }
 def_stdproc! { INVALID() => control::invalid }
 def_exit! { RETURN(a, b) => control::ret }