Neuropathology of peroxisomal disorders showed polymicrogyria in the cerebral and cerebellar cortices, neuronal heterotopia in the cerebral white matter, dysplasia of the inferior olivary nucleus and subependymal cyst in 6 cases of Zellweger syndrome (ZS), and diffuse loss of myelin sheath and mild polymicrogyria in a case of neonatal adrenoleukodystrophy. Developmental immunohistochemistry of catalase, acyl-CoA oxidase and ketoacyl-CoA thiolase revealed that positive reaction appears with neuronal and glial maturation. Diffuse dysmyelination may be related to maldevelopment of oligodendroglia, and migration disorder to abnormality of endothelial cells or radial glia, because both cells were positively stained in fetuses of 20 weeks of gestation and endothelial cells were rarely stained in ZS.