diff --git a/gym-unity/README.md b/gym-unity/README.md
index d963d59f73..f664c16e46 100755
--- a/gym-unity/README.md
+++ b/gym-unity/README.md
@@ -67,6 +67,8 @@ The returned environment `env` will function as a gym.
   be accessed from the `info` provided by `env.step(action)`.
 - Stacked vector observations are not supported.
 - Environment registration for use with `gym.make()` is currently not supported.
+- Calling env.render() will not render a new frame of the environment. It will
+  return the latest visual observation if using visual observations.
 
 ## Running OpenAI Baselines Algorithms
 
diff --git a/gym-unity/gym_unity/envs/__init__.py b/gym-unity/gym_unity/envs/__init__.py
index 0f70712947..322d83659b 100644
--- a/gym-unity/gym_unity/envs/__init__.py
+++ b/gym-unity/gym_unity/envs/__init__.py
@@ -278,6 +278,10 @@ def _get_vec_obs_size(self) -> int:
         return result
 
     def render(self, mode="rgb_array"):
+        """
+        Return the latest visual observations.
+        Note that it will not render a new frame of the environment.
+        """
         return self.visual_obs
 
     def close(self) -> None: