An 11-year-old Persian boy, born to consanguineous parents, manifested a progressive gait abnormality beginning at 5 years of age. A severe cerebellar disorder developed with associated dysfunction of the peripheral nervous system, but no sign of mental impairment. The sensory and motor nerve conduction velocities were greatly reduced, especially in the lower extremities. Cerebrospinal fluid protein was normal. Computed tomography and magnetic resonance imaging revealed leukoencephalopathy, especially in the cerebellum, but also in periventricular areas. The diagnosis of giant axonal neuropathy was established by biopsy of the sural nerve. The few previous histologic examinations have documented hyperplasia of the microfibrils which accumulate in the axons as well as in neurilemma, endothelial, and perineural cells. This is the first report of involvement of supraspinal portions of the central nervous system documented by postmortem examination after in vivo imaging methods corroborated the morphologic concomitants of the clinical symptoms.