Acetaminophen overdose is generally treated with oral N-acetylcysteine. While N-acetylcysteine is protective, an additional effective mode of treatment is desirable in large overdoses. A growing body of evidence suggests that cimetidine significantly reduces the hepatotoxicity of an acetaminophen overdose and that its hepatoprotective action may be additive to that of N-acetylcysteine. We report a case of acetaminophen overdose treated with oral N-acetylcysteine in conjunction with cimetidine by continuous i.v. infusion. The 4-h acetaminophen level was 410 micrograms/ml, and the highest measured level of serum glutamic oxaloacetic transaminase was 83 IU/L on day 3, indicating minimal hepatic toxicity.