A man of 35 years, who had had three attacks of subarachnoid hemorrhage in the previous 3 years, was admitted to hospital with complaints of headache and priapism. There had been intermittent priapism with abnormal acceleration of sexual desire since the first attack, and erection of the penis had persisted with intolerable pain after the last attack of subarachnoid hemorrhage. A carotid angiogram revealed an aneurysm at the junction of the left internal carotid and posterior communicating arteries. Clipping of the aneurysmal neck was successfully performed. However, priapism continued for 22 days after the operation and resulted in sexual impotence. The neurological problems of priapism are discussed with special reference to a hypothalamic lesion caused by the ruptured intracranial aneurysm in this report.