Psychoses are a common clinical problem in patients with Parkinson's disease. Treatment with typical neuroleptics or withdrawal of antiparkinsonian drugs may improve mental symptoms but will worsen the parkinsonism. Quetiapine (Seroquel), ICI 204,636, is a novel antipsychotic medication with a low potential for producing extrapyramidal side effects. In this open-label clinical study of 2 patients with Parkinson's disease, treatment with Seroquel successfully controlled psychotic symptoms without worsening of motor disability.Abstract Teaser