We report a 12-year-old boy presenting with smooth muscle antibody-positive auto-immune chronic active hepatitis. Suspicion of the diagnosis arose after a routine blood test which revealed abnormal liver function tests. In spite of the presence of cirrhosis and patchy necrosis on liver biopsy, our patient never showed any clinical feature of impaired liver function. This observation demonstrates that auto-immune hepatitis may exist for a long time before clinical symptoms appear and probably explains why some cases of auto-immune hepatitis finally present as fulminant liver failure.