In clinical trials, the dopamine agonist ropinirole has produced hallucinations and confusion rated as mild (4). We provide evidence here that ropinirole may induce or exacerbate severe, acute psychosis in a patient without Parkinson’s disease. This case is not conclusive in part because of the use of quetiapine. However, the rapidity and degree of improvement weigh in favor of a strong role for ropinirole, and the likelihood of such an effect with this medication stands to reason. Given the recognized relationship of dopaminergic function to psychosis, best known through the strong antipsychotic effects of dopamine antagonists, such an effect of exacerbating psychosis by a dopamine agonist seems almost predictable. We suggest that ropinirole, like all other dopaminergic agents, be used with caution in psychotic patients and those vulnerable to psychosis.