The patient, a 50-year-old man diagnosed 20 years previously with HD, first complained about tremor in the extremities and, in time, involuntary movements of the extremities and the body; gait difficulties and dysphagia added to his clinical presentation. He partially benefited from quetiapine 300 mg/day and clonazepam 2 mg/day during the last 1.5-year period. For the last 2 months, he has had insomnia, aggression, self-destructive behaviors, suicidal thoughts, and persecutory delusions, and his relatives took him to our outpatient clinic. On admission to our department, he scored 56 point on Unified Huntington’s Disease Rating Scale (UHDRS) motor section (oculomotor function, 12; hyperkinesias, 22; fine motor tasks, 9; parkinsonism, 4; gait, 9). We started aripiprazole treatment and gradually titrated up to 30 mg/day. In the first month of the treatment, we confirmed that irritability and persecutory delusions were markedly improved; his choreiform movements decreased significantly; and he finally became able to satisfy his own daily needs. At the end of the 16-month follow-up, we evaluated that his personal hygiene was significantly improved; dysarthria and dysphagia were completely ameliorated; and the intension and amplitude of choreiform movements were decreased. The patient still had no psychotic symptoms. We assessed that the last UHDRS total motor score was 20 (oculomotor function, 4; hyperkinesias, 6; fine motor tasks, 2; parkinsonism, 2; gait, 6).