A 60 year old woman with idiopathic Parkinson's disease had been prescribed thioridazine for schizophrenia. Five months after this was stopped, Sinemet also considered of dubious therapeutic value, was withdrawn. One week later she developed features of the neuroleptic malignant syndrome (NMS) accompanied by myoglobinuric renal failure. Post-mortem examination confirmed Lewy body degeneration in the substantia nigra. It is proposed that NMS may be caused by levodopa withdrawal in Parkinson's disease, and that it is withdrawal of dopaminergic drive that causes the syndrome.