Case report - We observed a serious symptomatic hepatocellular liver injury in an 85-year-old man treated with omeprazole for many years. Peak values for AST, ALT and AP were 1542 U/l (normal range 14-50), 1236 U/l (11-60) and 154 U/l (30-125) respectively. Abdominal CT scan was normal and viral serologic testing was negative. Omeprazole was discontinued and liver enzymes normalized in 12 days. The patient was known to suffer from ischemic heart disease and had had a myocardial infarction 6 months previously. He was reexposed to omeprazole and the level of liver enzymes rose again and normalized after stopping omeprazole. Despite the improvement of his liver function, the patient died 5 days later due to chronic congestive heart failure. Discussion - Five cases of omeprazole-induced liver injury have been reported to the Swiss Drug Regulatory Agency since 1990, among them two of cholestatic hepatitis and one of hepatic failure. The WHO Data Base has collected 13,630 ADRs related to omeprazole, with more than 80 cases of hepatitis, 60 of jaundice and about 40 of cholestatic hepatitis. In contrast, only one case of severe symptomatic hepatotoxicity is described in the literature. Clinical studies reported minimal increase of liver enzymes only, in 1-5% of cases. Conclusion - This case with reexposure, together with those reported internationally, suggests that hepatitis is a possible but obviously rare complication of omeprazole treatment. (C) 1998 John Wiley & Sons, Ltd.