A girl is described with a late-onset form of globoid cell leucodystrophy (GLD, Krabbe's disease). Data of this patient and seventeen reported patients with late-onset GLD and cerebroside-beta-galactosidase deficiency were compared with those of patients with classical early-infantile GLD. Three phenotypes of GLD are proposed, an early-infantile form, and two late-onset forms. Biochemical studies demonstrated residual activities of cerebroside-beta-galactocerebrosidase in the late-onset forms. The KM values were identical in the three GLD phenotypes. Autosomal recessive inheritance is likely for each of the subtypes. Complementation studies by somatic cell hybridization suggest that the mutations in early-infantile and late-onset GLD are allelic.