diff --git a/quick_extend_test.py b/quick_extend_test.py
new file mode 100644
index 0000000..b99ef89
--- /dev/null
+++ b/quick_extend_test.py
@@ -0,0 +1,20 @@
+import mcrfpy
+
+# Create grid
+t = mcrfpy.Texture("assets/kenney_ice.png", 16, 16)
+g = mcrfpy.Grid(5, 5, t, (0, 0), (100, 100))
+
+# Create some entities
+entities = [mcrfpy.Entity((i, i), t, i, g) for i in range(3)]
+
+# Test extend
+print(f"Initial entities: {len(g.entities)}")
+g.entities.extend(entities)
+print(f"After extend: {len(g.entities)}")
+
+# Test with tuple
+more = (mcrfpy.Entity((3, 3), t, 3, g), mcrfpy.Entity((4, 4), t, 4, g))
+g.entities.extend(more)
+print(f"After second extend: {len(g.entities)}")
+
+print("✓ EntityCollection.extend() works!")
\ No newline at end of file
diff --git a/src/UIGrid.cpp b/src/UIGrid.cpp
index 0d08328..7a2f9ed 100644
--- a/src/UIGrid.cpp
+++ b/src/UIGrid.cpp
@@ -637,9 +637,47 @@ PyObject* UIEntityCollection::remove(PyUIEntityCollectionObject* self, PyObject*
     return Py_None;
 }
 
+PyObject* UIEntityCollection::extend(PyUIEntityCollectionObject* self, PyObject* o)
+{
+    // Accept any iterable of Entity objects
+    PyObject* iterator = PyObject_GetIter(o);
+    if (iterator == NULL) {
+        PyErr_SetString(PyExc_TypeError, "UIEntityCollection.extend requires an iterable");
+        return NULL;
+    }
+    
+    PyObject* item;
+    while ((item = PyIter_Next(iterator)) != NULL) {
+        // Check if item is an Entity
+        if (!PyObject_IsInstance(item, PyObject_GetAttrString(McRFPy_API::mcrf_module, "Entity"))) {
+            Py_DECREF(item);
+            Py_DECREF(iterator);
+            PyErr_SetString(PyExc_TypeError, "All items in iterable must be Entity objects");
+            return NULL;
+        }
+        
+        // Add the entity to the collection
+        PyUIEntityObject* entity = (PyUIEntityObject*)item;
+        self->data->push_back(entity->data);
+        entity->data->grid = self->grid;
+        
+        Py_DECREF(item);
+    }
+    
+    Py_DECREF(iterator);
+    
+    // Check if iteration ended due to an error
+    if (PyErr_Occurred()) {
+        return NULL;
+    }
+    
+    Py_INCREF(Py_None);
+    return Py_None;
+}
+
 PyMethodDef UIEntityCollection::methods[] = {
     {"append", (PyCFunction)UIEntityCollection::append, METH_O},
-    //{"extend", (PyCFunction)UIEntityCollection::extend, METH_O}, // TODO
+    {"extend", (PyCFunction)UIEntityCollection::extend, METH_O},
     {"remove", (PyCFunction)UIEntityCollection::remove, METH_O},
     {NULL, NULL, 0, NULL}
 };
diff --git a/src/UIGrid.h b/src/UIGrid.h
index 0e041a2..1e3f2aa 100644
--- a/src/UIGrid.h
+++ b/src/UIGrid.h
@@ -77,6 +77,7 @@ class UIEntityCollection {
 public:
     static PySequenceMethods sqmethods;
     static PyObject* append(PyUIEntityCollectionObject* self, PyObject* o);
+    static PyObject* extend(PyUIEntityCollectionObject* self, PyObject* o);
     static PyObject* remove(PyUIEntityCollectionObject* self, PyObject* o);
     static PyMethodDef methods[];
     static PyObject* repr(PyUIEntityCollectionObject* self);
diff --git a/tests/issue27_entity_extend_test.py b/tests/issue27_entity_extend_test.py
new file mode 100644
index 0000000..41fd744
--- /dev/null
+++ b/tests/issue27_entity_extend_test.py
@@ -0,0 +1,105 @@
+#!/usr/bin/env python3
+"""
+Test for Issue #27: EntityCollection.extend() method
+
+Verifies that EntityCollection can extend with multiple entities at once.
+"""
+
+def test_entity_extend(timer_name):
+    """Test that EntityCollection.extend() method works correctly"""
+    import mcrfpy
+    import sys
+    
+    print("Issue #27 test: EntityCollection.extend() method")
+    
+    # Create test scene and grid
+    mcrfpy.createScene("test")
+    ui = mcrfpy.sceneUI("test")
+    
+    # Create grid with texture
+    texture = mcrfpy.Texture("assets/kenney_ice.png", 16, 16)
+    grid = mcrfpy.Grid(10, 10, texture, (10, 10), (400, 400))
+    ui.append(grid)
+    
+    # Add some initial entities
+    entity1 = mcrfpy.Entity((1, 1), texture, 1, grid)
+    entity2 = mcrfpy.Entity((2, 2), texture, 2, grid)
+    grid.entities.append(entity1)
+    grid.entities.append(entity2)
+    
+    print(f"✓ Initial entities: {len(grid.entities)}")
+    
+    # Test 1: Extend with a list of entities
+    new_entities = [
+        mcrfpy.Entity((3, 3), texture, 3, grid),
+        mcrfpy.Entity((4, 4), texture, 4, grid),
+        mcrfpy.Entity((5, 5), texture, 5, grid)
+    ]
+    
+    try:
+        grid.entities.extend(new_entities)
+        assert len(grid.entities) == 5, f"Expected 5 entities, got {len(grid.entities)}"
+        print(f"✓ Extended with list: now {len(grid.entities)} entities")
+    except Exception as e:
+        print(f"✗ Failed to extend with list: {e}")
+        raise
+    
+    # Test 2: Extend with a tuple
+    more_entities = (
+        mcrfpy.Entity((6, 6), texture, 6, grid),
+        mcrfpy.Entity((7, 7), texture, 7, grid)
+    )
+    
+    try:
+        grid.entities.extend(more_entities)
+        assert len(grid.entities) == 7, f"Expected 7 entities, got {len(grid.entities)}"
+        print(f"✓ Extended with tuple: now {len(grid.entities)} entities")
+    except Exception as e:
+        print(f"✗ Failed to extend with tuple: {e}")
+        raise
+    
+    # Test 3: Extend with generator expression
+    try:
+        grid.entities.extend(mcrfpy.Entity((8, i), texture, 8+i, grid) for i in range(3))
+        assert len(grid.entities) == 10, f"Expected 10 entities, got {len(grid.entities)}"
+        print(f"✓ Extended with generator: now {len(grid.entities)} entities")
+    except Exception as e:
+        print(f"✗ Failed to extend with generator: {e}")
+        raise
+    
+    # Test 4: Verify all entities have correct grid association
+    for i, entity in enumerate(grid.entities):
+        # Just checking that we can iterate and access them
+        assert entity.sprite_number >= 1, f"Entity {i} has invalid sprite number"
+    print("✓ All entities accessible and valid")
+    
+    # Test 5: Invalid input - non-iterable
+    try:
+        grid.entities.extend(42)
+        print("✗ Should have raised TypeError for non-iterable")
+    except TypeError as e:
+        print(f"✓ Correctly rejected non-iterable: {e}")
+    
+    # Test 6: Invalid input - iterable with non-Entity
+    try:
+        grid.entities.extend([entity1, "not an entity", entity2])
+        print("✗ Should have raised TypeError for non-Entity in iterable")
+    except TypeError as e:
+        print(f"✓ Correctly rejected non-Entity in iterable: {e}")
+    
+    # Test 7: Empty iterable (should work)
+    initial_count = len(grid.entities)
+    try:
+        grid.entities.extend([])
+        assert len(grid.entities) == initial_count, "Empty extend changed count"
+        print("✓ Empty extend works correctly")
+    except Exception as e:
+        print(f"✗ Empty extend failed: {e}")
+        raise
+    
+    print(f"\n✅ Issue #27 test PASSED - EntityCollection.extend() works correctly")
+    sys.exit(0)
+
+# Execute the test after a short delay
+import mcrfpy
+mcrfpy.setTimer("test", test_entity_extend, 100)
\ No newline at end of file