Huntington's disease (HD) is a hereditary disorder clinically characterized by involuntary movements, cognitive decline and psychiatric symptoms. We report on a patient with HD, whose involuntary movements and psychiatric symptoms were clinically improved with perospirone, a second-generation antipsychotic agent with antagonistic effects on serotonin 5-HT(2A) and dopamine D(2) (D(2)) receptors, as well as a unique agonistic effect on serotonin 5-HT(1A) (5-HT(1A)) receptors. The fact that perospirone antagonizes D(2) receptors could explain its effects on the hyperkinetic syndrome, while its agonistic effects on 5-HT(1A) receptors may explain the amelioration of psychiatric symptoms (fear and anxiety) in this patient. Future studies would be valuable to elucidate the utility of perospirone for the treatment of involuntary movements and psychiatric symptoms in HD.