The authors review the course of disease in 130 patients (87 HBsAg-positive and 43 HBsAg-negative) with chronic active hepatitis (CAH) observed in the last six years. Patients were treated with prednisone (36 HBsAg-positive an 8 HBsAg-negative), azathioprine (7 HBsAg-positive and 12 HBsAg-negative) or a combination of prednisone and azathioprine (23 HBsAg-positive and 14 HBsAg-negative), or remained untreated (21 HBsAg-positive and 9 HBsAg-negative). Among HBsAg-positive patients improvement was observed in 54% of the 66 patients treated, and in none of the 21 untreated patients (P less than 0.001). Treatment did not modify the course of the disease in HBsAg-negative patients with CAH; this is probably related either to the small number of patients in each treatment group, or to geographical differences. Furthermore treatment was not effective in patients older than 40 years, whether HBsAg-positive or HBsAg-negative. Three out of 87 HBsAg-positive patients, and two out of the 43 HBsAg-negative patients had died by the end of the observation period irrespective of treatment. Full remission with clearance of HBsAg was observed only in one patient after 4 years of treatment with steroids.