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