We retrospectively reviewed the clinical, biochemical and histological features of 867 patients with biopsy-proven CAH observed in 12 Italian Liver Units for at least one year. Either HBsAg positive or HBsAg negative patients (473 and 394 patients, respectively) were left untreated, or were treated with one of the following regimens: a) prednisolone or prednisone 10 to 30 mg daily, referred to as Steroids; b) azathioprine 50 to 100 mg daily; c) prednisolone or prednisone 10 to 20 mg daily associated with azathioprine 50 to 100 mg daily, referred to as Combination. The outcome was evaluated on the basis of clinical, biochemical and histological parameters. Among the 473 patients with HBsAg positive CAH those treated with combination, as compared to those untreated, more frequently, improved (P less than 0.001), and less frequently deteriorated (P less than 0.001). Under Steroids or Azathioprine improvement was more frequent than in untreated patients, but deterioration was not prevented. The results were similar among the 394 HBsAg negative patients. The data indicate that combination is effective in treating either HBsAg positive CAH or HBsAg negative CAH.