It is well known that the myoglobinuric acute renal failure caused by drugs is an important clinical aspect of nephrology. On the other hand, neuroleptic malignant syndrome is an uncommon, but potentially fatal, idiosyncratic reaction to neuroleptics and is characterized by muscular rigidity, fever, autonomic dysfunction and altered consciousness. The most common serious complication of malignant syndrome is rhabdomyolysis. We investigated 10 cases with acute renal failure induced by haloperidol and other neuroleptics. At the time they developed acute renal failure, the patients were taking a wide variety of medications. However, seven of the patients who developed acute renal failure, had received haloperidol, phenothiazine and anticholinaergic drugs, and 2 cases with acute renal failure were taking lithium. Characteristic clinical manifestations of malignant syndrome were observed in 7 patients who had been administered haloperidol orally or intravenously. All of the patients with acute renal failure induced by haloperidol, lithium and other neuroleptics were treated succsessfully with blood purification therapy (HD or HDF). We concluded that acute renal failure associated with malignant syndrome evoked by haloperidol is an indication for blood purification therapy.