We performed pathological studies on the central and peripheral nervous systems of cases with infantile neuroaxonal dystrophy (INAD). Numerous spheroid bodies in the central and peripheral nervous systems, were seen and divided into large spheroid bodies (LSB) and small spheroid bodies (SSB) photo-microscopically. LSB had a relation to some specific neurons with weak expression of neuron specific enolase, neurofilament and chromogranin using PAP method. SSB showed a relation to the axon without immunohistochemical expression of neuron specific enolase, neurofilament, glial fibrillary acidic protein, myelin basic protein, chromogranin, S 100 protein or antitrypsin. LSB were prominent in the posterior column, gracile nucleus, cuneate nucleus, and the tegmentum of the midbrain and the pons associated with neuronal loss and gliosis. SSB were observed in the thalamus, basal ganglia and the cerebral cortex. The cerebellum was sclerotic with few microtubule-like structures disposed in a dense network in association with degenerated mitochondria. Similar changes were observed in the sural nerves, autonomic nerve endings in the skin, and the nerve plexus of the digestive tract. Although INAD is a generalized neurodegenerative disease, it is suggested that the primary disorder might occur in the neurons and axons of the sensory tracts.