A 24-year-old male, who suffered since childhood from a progressive form of ataxia associated with peripheral neuropathy, was found severely deficient in serum vitamin E. He walked with bilateral aid and presented severe dysmetria of the limbs and dysarthric speech; muscular strength and trophism were slightly diminished in the distal muscles of four limbs and there was hypotonia of the arms; he presented absent deep tendon reflexes, bilateral Babinski's sign, reduced proprioception at four limbs, pes cavus and fasciculations of the tongue. Intestinal fat malabsorption and other gastrointestinal or haematological conditions associated with deficiency of this vitamin were ruled out. In this patient, after 2 years of a daily supplement of high doses of vitamin E, a further progression of the disease was not observed and, moreover, the neurophysiological characteristics of his neuropathy appeared clearly improved. A longitudinal evaluation of serum vitamin E levels showed values in the normal range after 13 months of therapy. The patient had molecular genetic analysis of chromosome 8 and was found homozygous for the unusual mutation 513insTT in the alpha-tocopherol transfer protein gene.