Autoimmune chronic active hepatitis, now often refereed to as simply autoimmune hepatitis has been recognised for nearly 50 years. Typically, the diseases arises in a young woman who presents with an acute hepatitic illness and complains of lethargy, arthralgia, oligomenorrhoea, and fluctuating jaundice. For the purposes of clinical trials and research, guidelines for establishing the diagnosis have been published recently, but in clinical practise it is diagnosed when there is a histological picture of chronic active hepatitis together with immunological features (high levels of immunoglobulin G and serum autoantibodies) in the absence of other known causes of the histological picture. Controlled trials in the 1970s confirm the efficacy of immunosuppressive therapy in terms of improvement of both symptoms and survival. Treatment protocols based on prednisolone and azathioprine have been refined over the past 20 years so that the prognosis is now good and side effects from treatment are usually minimal.