In transcondylar approach, the anatomical landmarks should be well known in order to make a safe occipital condyle resection. The distance between the intracranial edge of the hypoglossal canal and posterior margin of the occipital condyle is important for a safe occipital condyle resection, and it was found to be 12.55 +/-0.05 mm in our study. Approximately 12 mm occipital condyle resection can be made without giving damage to the neural tissue. This value is appropriate to the (1/2) of the occipital condyle.