The authors report a case of pituitary apoplexy occurring several hours after carotid angiography. The event was associated with stupor, focal headache, and left hemiparesis. Repeat angiography demonstrated intracranial occlusion of the right internal carotid artery. At surgery, a hemorrhagic pituitary adenoma was found to be compressing the internal carotid artery, and the removal of the tumor resulted in restoration of flow. The mechanism, presenting symptoms and signs, and treatment of pituitary apoplexy causing compression of a major vessel are discussed.