Ninety-six chronic asymptomatic HBsAg carriers underwent liver biopsy. Liver histology was normal in 5 cases, showed nonspecific changes in 67, chronic persistent hepatitis in 18, and chronic-active hepatitis in 6. Seventy-four patients were followed for up to 105 months (mean 80 months) in order to evaluate the occurrence of clinical, biochemical, serological or histological changes. Only two patients cleared the HBsAg, respectively 10 and 96 months after undergoing liver biopsy; the latter patient became anti-HBs positive 6 months after he cleared HBsAg. All 10 patients who initially were negative for both HBeAg and anti-HBe became anti-HBe positive during follow-up. All 4 patients who were HBeAg positive at the time of liver biopsy cleared HBeAg 6 to 39 months thereafter. Two of them became anti-HBe positive. None of the patients initially HBeAg negative became positive for this antigen during follow-up. Significant increases of serum transaminases were observed in 5 patients; in one superinfection by delta agent was documented, the other 4 being constantly anti-delta negative. Three of the latter patients underwent repeat liver biopsy, which showed progression from minimal changes to chronic persistent hepatitis in one, and from minimal changes to chronic active hepatitis in another. In the third patient, repeat biopsy showed persistence of chronic persistent hepatitis. CONCLUSIONS chronic hepatitis occurs in about 25% of chronic asymptomatic HBsAg carriers; clearance of HBsAg is a rare event among these patients; the HBe system has little diagnostic or prognostic value; delta superinfection is rare; however, deterioration of liver histology may occur even in the absence of delta superinfection.