ABSTRACT:We performed a double-blind cross-over study with amantadine hydrochloride in 12 patients with Friedreich's disease and 2 with autosomal dominant cerebellar ataxia. Patients were randomly assigned to a placebo-amantadine or amantadine-placebo sequence. The interval between the treatments was two weeks. Patients were graded according to a functional ataxia scoring scale and videotaped in basal conditions and 90 min after a single oral dose of 100 mg amantadine or placebo. Three evaluators independently scored the videotapes. Statistical analysis showed no significant effect of amantadine in Friedreich's disease.