Pathologic studies were made in an infant with the tuberous sclerosis complex who was killed accidentally at the age of 18 months. The child had not had any seizures. The only other associated malformation was a small cardiac rhabdomyoma. The gyral pattern was normal. The subcortical nodules consisted of monster cells of glial origin, some of which showed a transition into more normal astrocytes. Abnormal neurons were not seen. The cortical lamination was preserved except in those zones in which the predominant subcortical nodules extended into the lower lamina of the cortex. It appears that early in the evolution of the typical tubers, this disease may manifest itself as a dysgenetic astrocytosis.