Infarction of the territory supplied by the contralateral superior cerebellar artery in cases of descending transtentorial herniation has not been reported. The authors experienced a primitive neuroectodermal tumor in a patient whose consciousness deteriorated transiently due to descending transtentorial herniation. On the magnetic resonance imaging taken 8 days after the herniation, lesions thought to be infarction of territories supplied by the ipsilateral posterior cerebral artery and the contralateral superior cerebellar artery were noted. The possible mechanism of this peculiar pattern of infarction is discussed.