Twenty-two patients with HBsAg positive acute viral hepatitis have been followed-up for two years after the acute episode. Besides the usual clinical, pathological and biological examinations, the following tests were carried out: serum HBsAg: circulating T and B lymphocytes: serum IgG, IgA, IgM: leukocyte migration test to HBsAg; serum complement: autoantibodies, rheumatoid factors, cryoglobulins, alpha-fetoprotein. Serum HBsAg persistence was correlated with some features of the acute episode: protracted clinical form: recurrences or relapses; splenomegaly; decrease of circulating T-lymphocytes; presence of lymphocyte sensibilization to HBsAg. Among the seven serum HBsAg carriers, three developed a chronic hepatitis. The state of healthy chronic HBsAg carrier was associated with high levels of serum IgA (over 300 IU/ml). A chronic hepatitis has been also diagnosed in four out of the 15 patients who cleared their serum HBsAg. The presence, on the one hand, of a chronic hepatitis among the patients who cleared their HBsAg and, on the other hand, its absence in some of the HBsAg carriers suggest that HBsAg persistence is not a sine qua non condition for the development of the chronic liver disease. The onset of autoimmune phenomena due to the disturbance of immunologic homeostasis and perhaps other genetic or environmental factors seemingly allow the perpetuation of a hepatic damage.