Angulate lysosomes with intralysosomal trilamellar structures were first described in patients with metabolic peroxisomal disorders. In this ultrastructural study of skin biopsies of 139 patients with degenerative neurological disorders and 45 patients with static encephalopathies, we observed angulate lysosomes with similar ultrastructure exclusively in degenerative neurological disorders. They were found in only a few cases (8%), but especially in patients with degenerative metabolic disorders (72%). Because they were never observed in patients with static encephalopathies, angulate lysosomes in the skin would seem to be a sign of progressive encephalopathy. The great majority (75%) of angulate lysosomes were associated with neuronal ceroid-lipofuscinosis (NCL). Their presence in skin biopsy could suggest the diagnosis of NCL and eliminate a peroxisomal disorder. In the latter pathology, angulate lysosomes, numerous in the liver and in the brain, were never observed in the skin. As described in pigmentary retinopathy, a conspicuous feature of NCL, we suggest that in this lysosomal storage disorder, the angulate lysosomes in skin biopsies could result from the phagocytosis of melanin.