We report a patient with idiopathic Parkinson's disease who underwent bilateral deep brain stimulation (DBS) of the nucleus subthalamicus (STN) and developed visual hallucinations (VH) while taking no medications only when the DBS was turned on. The hallucinations resolved when the stimulator was turned off. The phenomenology and the prompt response to clozapine suggest that DBS-induced VH mimic pharmacologically-induced VH.