Severe adverse reactions to neuroleptic medications are not uncommon and include the neuroleptic malignant syndrome, rhabdomyolysis, and acute renal failure. The neuroleptic malignant syndrome consists of hyperthermia, diaphoresis, tachycardia, tachypnea, abnormal blood pressure, alteration of consciousness, and extrapyramidal rigidity. Rhabdomyolysis--which might be due to hyperthermia, muscle rigidity, and/or metabolic changes in skeletal muscle function--results in acute renal failure. We report a patient with rhabdomyolysis and acute renal failure that developed after large doses of haloperidol were given, but without muscle rigidity or hyperthermia. This patient's presentation illustrates that high-dose haloperidol therapy might cause rhabdomyolysis and acute renal failure without significant rigidity or hyperthermia.