diff --git a/aio_pika/pool.py b/aio_pika/pool.py
index 93fc4080..ecf968b4 100644
--- a/aio_pika/pool.py
+++ b/aio_pika/pool.py
@@ -142,6 +142,9 @@ async def __aexit__(
 
         await asyncio.ensure_future(self.close())
 
+    def __len__(self) -> int:
+        return len(self.__item_set)
+
 
 class PoolItemContextManager(Generic[T], AsyncContextManager):
     __slots__ = "pool", "item"
diff --git a/tests/test_pool.py b/tests/test_pool.py
index 661143fc..ee02db78 100644
--- a/tests/test_pool.py
+++ b/tests/test_pool.py
@@ -17,6 +17,7 @@ async def create_instance():
         return counter
 
     pool = Pool(create_instance, max_size=max_size, loop=loop)
+    assert len(pool) == 0
 
     async def getter():
         nonlocal counter, pool
@@ -34,6 +35,8 @@ async def getter():
 
     assert counter == max_size
 
+    assert len(pool) == max_size
+
 
 class TestInstanceBase:
     class Instance(PoolInstance):