A review of the literature on the developmental outcome of medically and surgically treated symptomatic infantile spasms (IS) indicates that poor seizure control, severe mental retardation, and marked behavioral disorders are found at long-term outcome of symptomatic IS. The 2-year outcome findings of the UCLA Pediatric Epilepsy Surgery Research Group in children with symptomatic infantile spasms and in children with early onset intractable symptomatic epilepsy other than IS (non-IS) demonstrate impaired development of cognition, language, and social communication despite improved seizure control. The social communication deficits of these children are similar to those found in autistic children. Finally, the underlying pathology of the resected brain, rather than ongoing seizures and seizure type, plays an important role in development of the remaining brain tissue and the outcome of early onset symptomatic IS and non-IS.