A total of 159 hemophiliacs (149 treated) from our geographical area were screened in 1983 for serological evidence of HBV infection and biochemical evidence of liver disease. All were asymptomatic. HBsAg was detected in 16 cases (10%); anti-HBs and anti-HBc in 106 (67%); 19 (12%) subjects were susceptible to HBV. The HBV infection rate evaluated in 70 patients followed-up from 1980 to 1983 was 28% per year. The cumulative risk of HBV infection as well as the rate of seroconversion to HBV increased with increasing age and with increasing frequency of treatment given during the last 12 months. Anti-delta was detected in the serum of 5 (28%) out of 13 HBsAg-positive cases. Follow-up data showed that in 61% of subjects with liver dysfunction, hepatic damage could not be accounted for by HBV infection. AST and/or gamma-globulin increase was detected in 80% of patients. Abnormalities were more pronounced in HBsAg-positive cases and among them in subjects carrying anti-delta. Further follow-up studies are needed to clarify the long-term prognosis of liver disease in hemophiliacs.