A 25 year old patient presented with recurrent prolonged episodes of life-threatening coma varying from 3 to 10 days. The clinical recovery was slow. The history and technical examinations led to the diagnosis of basilar artery migraine (BAM). The etiology of the coma episodes is thought to be related to ischemic dysfunction of the rostral part of the brainstem due to severe spasm of the basilar artery demonstrated by arteriography. Exceptional are the recurrent prolonged coma episodes of sudden onset, the severe spasm of the basilar artery, and the suppression-burst and FIRDA pattern on the EEG examinations during the coma episodes.