We report four cases of niacin-induced hepatotoxicity. All four patients were using sustained-release niacin preparations. When they stopped taking niacin, symptoms and laboratory abnormalities resolved. Two of the patients had focal fatty infiltration of the liver on imaging studies, a presentation of niacin hepatotoxicity not previously described. One patient had a coagulopathy even though aminotransferase levels were only mildly elevated. We recommend that patients using sustained-release preparations of niacin have periodic monitoring of liver enzymes and that the preparation be discontinued if any abnormalities develop.