Neuroleptic malignant syndrome is a potentially lethal side effect of neuroleptic drugs, characterized by fever, muscle rigidity, autonomic dysfunction, and altered consciousness. A 50-year-old female hospitalized three times in the past for psychiatric treatment was admitted to Umayabashi Hospital for treatment of a relapse of a schizophrenic psychosis. She had received 50 mg of chlorpromazine and one tablet of Vegetamin-A (chlorpromazine 25 mg, promethazine 12.5 mg, phenobarbital 40 mg). Approximately 24-36 hours later, the patient became febrile and lost consciousness, and eight days later, acute renal failure occurred with muscle rigidity. She was transported to Maebashi Red Cross Hospital to receive hemodialysis. On admission, the laboratory studies showed high levels of serum creatine phosphokinase, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, creatinine and blood urea nitrogen. She underwent hemodialysis for treatment of acute renal failure and recovered from it after 16 sessions of hemodialysis.