The efficacy of amantadine, a dopamine-releasing agent and antagonist of the N-methyl-D-aspartate glutamate receptor, was evaluated in patients with olivopontocerebellar atrophy. By contrast to an untreated control group whose terminal performance deteriorated on 8 of 8 measurements of reaction time and movement time, patients treated with amantadine for a mean duration of over 40 months had improved performances in 1 of 4 reaction time measurements and in 3 of 4 movement time measurements and remained stable on the others. These results demonstrate long-term benefits of amantadine in olivopontocerebellar atrophy-induced deficits of movement initiation and movement completion.