Hemiballism is a relatively rare hyperkinetic disorder; treatment is based mainly on neuroleptics and drugs that decrease release of dopamine. We report the cases of two patients with hemiballism. After a period of 1 month of nonresponsiveness to haloperidol, amelioration of ballistic movements was observed only a few days after the initiation of clozapine therapy (50 mg/day). Our report suggests that clozapine may be a valuable alternative for patients with hemiballism.