The involvement of the central nervous system in fucosidosis is related to severe lesions of both nerve and glial cells. The morphology of cells degeneration is characterized by both vacuoli containing water-soluble fuco-derivatives (fuco-oligosaccharides) and/or granular substances probably constituted by fuco-sphingolipds. The cerebral cortex is the most severely affected. The involvement of the white matter is related to the glial cells degeneration. The relationship between the morphology of nerve and glial cells lesions, and the accumulation of oligosaccharides and sphingolipids following the absence of alpha-L-fucosidase, is briefly discussed.