Lafora's AFORA'S disease is a rare form of myoclonus epilepsy.1It is characterized by myoclonus, generalized convulsions, and progressive mental deterioration which begin during adolescence. Death within four to ten years has been the inevitable outcome in all reported cases. This report describes the ultrastructure of the inclusion bodies found in cerebral cortical biopsy specimens from two patients with Lafora's disease. The ultrastructure of liver and gastrocnemius muscle are also briefly described. Detailed clinical, genetic, histopathologic, and biochemical data have been separately reported2-4so that only brief clinical reports are given here. Report of Cases CASE1.—A 19-year-old white boy, product of the equivalent of double-first cousin consanguineous parentage, had developed normally until age 17. Generalized convulsions began and soon were associated with diffuse asynchronous myoclonus, mental deterioration, and dystaxia. A cerebral cortical biopsy showed neuronal inclusion bodies of the Lafora type. Biochemical assays of glycogen and