Huntington's disease is a hereditary and progressive disease of the central nervous system. Sudden and irregular hyperkinesias are prominent. Psychopathological findings are very frequent and often proceed the decline of motor functions for years. Almost all the patients develop a dementia in later stages of the illness. This case study shows the treatment of a patient with Huntington's disease, verified by genetic analysis, with the atypical antipsychotic drug amisulpride. In this case the psychiatric disturbances and cognitive impairments were the only signs of the disease. The treatment showed an impressive improvement. Neuropsychological aspects of the disease are discussed.