The sebaceous nevus syndrome is sometimes associated with hemimegalencephaly and a group of related abnormalities including ipsilateral gyral malformation, mental retardation, seizures, especially infantile spasms, and facial hemihypertrophy. This combination has been described as the "neurological variant of epidermal nevus syndrome." Other brain malformations have been reported only rarely. We report on a child with a subtle sebaceous nevus associated with hemimegalencephaly who also had agenesis of the corpus callosum and Dandy-Walker malformation.