Neuropathologic changes in patients with cystic fibrosis include dystrophic axons in the nucleus gracilis and demyelination of the fasciculus gracilis. We reviewed 43 autopsy cases of cystic fibrosis to determine the incidence and severity of these changes. Sixty-six percent of patients developed dystrophic axons. There was a direct correlation between severity of neuroaxonal dystrophy and duration of disease. Demyelination of the fasciculus gracilis occurred in 11%. The neuropathology of cystic fibrosis resembles that of vitamin E deficiency in animals. However, vitamin E replacement failed to prevent neuropathologic changes in these patients.