We report four patients with infantile spasms and the congenital bilateral perisylvian syndrome. Onset of spasms occurred during the first 6 months of life. Response to corticotropin treatment was prompt and resulted in resolution of seizures in all patients. Epilepsy developed in the four children after an interval of 2 to 12 years. Developmental outcome was variable; three were severely restricted and one was married and lived independently. Imaging studies revealed bilateral perisylvian lesions characteristic of polymicrogyria. Infantile spasms may be the presenting seizure type in some patients with the congenital bilateral perisylvian syndrome.