The juvenile-onset subtype of the neuronal ceroid lipofuscinoses (JNCL) is well known [Hofman, ISBN90-71534-19-7 1990] and ultrastructurally characterized by fingerprints and/or curvilinear bodies in many cell types. Linkage studies indicated a most likely location for CLN3, the gene involved in JNCL, in the interval between loci D16S297 and D16S57, within close proximity of the loci D16S298 and D16S299 [Mitchison et al., Genomics 22:465-468, 1993]. We present two sibs with a late onset progressive disease of mental deterioration, progressive macular degeneration, motor disturbances, and epilepsy. Histological symptoms of neuronal ceroid lipofuscinosis and ultrastructural granular osmiophilic deposits (GROD) in lymphocytes and neurons are found. Individual haplotypes at polymorphic marker loci on chromosome 16 were constructed to determine whether JNCL with GROD is linked to the CLN3 locus.