Four patients with vitamin E deficiency and sensory ataxia were studied using [18F]dopa positron emission tomography. The 2 most disabled patients, who had severe and prolonged vitamin E deficiency due to abetalipoproteinemia, showed reduced [18F]dopa uptake in both putamen and caudate. Putaminal uptake was in a similar range to that seen in Parkinson's disease. Studies of [3H]mazindol binding in the striatum of vitamin E--deficient rats indicated a reduced number of dopamine terminals, which was most severe in ventrolateral striatum. These observations suggest that severe and prolonged vitamin E deficiency results in loss of nigrostriatal nerve terminals, and support the hypothesis that oxidative stress may contribute to the etiology of Parkinson's disease.