This study was designed to evaluate the responses of conventional doses of corticosteroid therapy alone, and together with azathioprine in HBsAg-positive severe chronic active hepatitis. This study indicated that conventional doses of prednisolone therapy alone or together with azathioprine in HBsAg-positive severe chronic active hepatitis were followed definitely by clinical, biochemical and even histological improvement. Initial therapy of HBsAg-positive chronic active hepatitis with conventional doses of prednisolone alone or together with azathioprine has no advantage over therapy with maintenance of prednisolone alone with 15mg per day since the beginning of the treatment. However, azathioprine with lower doses of prednisolone may have a place in the treatrnent of chronic active hepatitis when there is no initial response to prednisolone alone or ivhen major prednisolone side effects occur. HBsAg was not converted to negative after the treatment with corticosteroid. However, rate of occurrence of hepatocellular carcinoma in late stage in patients treated with cortco- steroid was not exceed in patients without such treatment. It is concluded that the presence of I-iBsAg does not preclude a satisfactory clinical and histological responses to steroid therapy.