Six of 81 (7.4%) patients with medically intractable epilepsy treated by selective cortical excision at The Hospital for Sick Children, Toronto, Canada, since 1974 were found to have inflammatory changes in the excised specimens of cerebral cortex. The clinical and histopathological findings in these cases resemble the chronic encephalitic syndrome described by Rasmussen. We confirm the unsatisfactory seizure control and the guarded neurological and intellectual prognosis that has been associated with Rasmussen syndrome.