We described a 32-year-old woman with Huntington's disease (HD) who presented with severe chorea, psychosis and cognitive abnormalities. We started risperidone at 2 mg p.o./d and increased to 4 mg p.o./d after six weeks. Psychotic and motor symptoms were markedly improved. Since there was no change in cognitive functions, we added memantine at 5 mg p.o./d and gradually increased the dose to 20 mg p.o/d after five weeks. We continued risperidone and memantine for nearly six months. The patient did not show any progression of cognitive symptoms or motor abnormalities. We did not observe any psychotic symptoms.