Four patients with left-sided posterior cerebral artery infarction developed acute confusional states. Fifteen additional patients with confusion following unilateral posterior cerebral artery infarction were identified from a review of the literature; in 14 the lesion was left sided. Destruction or disconnection of dominant hemisphere neocortex from limbic structures, resulting in impairment of focal attention, loss of linguistically organized memory, and/or disruption of temporal sequencing may be responsible for this syndrome.