The neuronal ceroid lipofuscinoses are clinical disorders associated with the accumulation of autofluorescent waxy pigments within cells of several different tissues. Such syndromes always have neurological manifestations. Variations in clinical course, genetics, pathogenesis, and possibly treatment occur in each of the several forms listed under this category. Ten subtypes have now been recognized: (1) chronic, juvenile (Batten type); (2) acute, late infantile (Bielschowsky type); (3) subacute-chronic, adult (Kufs type); (4) acute, infantile (Santavuori-Haltia type); (5) congenital (Norman-Wood type); (6) acute, adult (Zeman-Dyken type); (7) acute-subacute childhood (Bielschowsky variant); (8) chronic, childhood with pervasiveness (Edathodu-Dyken type); (9) chronic, infantile with autism (Dyken type); and (10) chronic, juvenile with ataxia and spasticity (Dyken type). By far the most common of these are the first four disorders listed. It is proposed that this present classification of neuronal ceroid lipofuscinosis is more comprehensive than previous ones and fails to support the hypothesis that this disorder represents a unitary disease process, rather than different diseases with similar characteristics. At present, each of the neuronal ceroid lipofuscinosis types are of unknown etiology.