Despite recent interest in the pathogenesis of the autism spectrum disorders (pervasive developmental disorders), neuropathological descriptions of brains of individuals with well documented clinical information and without potentially confounding symptomatology are exceptionally rare. Asperger syndrome differs from classic autism by lack of cognitive impairment or delay in expressive language acquisition. We examined the 1,570 g brain of a 63 year old otherwise healthy mathematician with an Autistic Spectrum Disorder of Asperger subtype. Except for an atypical gyral pattern and megalencephaly, we detected no specific neuropathologic abnormality. Taken together, the behavioral data and pathological findings in this case are compatible with an early neurodevelopmental process affecting multiple neuroanatomic networks, but without a convincing morphologic signature detectable with routine neuropathologic technology.