72 Chinese patients who had been positive for hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) for more than six months with stable serum hepatitis B virus DNA were randomised to receive recombinant alpha 2-interferon at doses of 2.5, 5, or 10 X 10(6) U/m2 intramuscularly thrice weekly for 12-24 weeks, or no treatment. 6 (11%) of 54 treated and 1 (6%) of 18 control patients became HBeAg-negative at the end of therapy or after 24 weeks of follow-up. 9 (17%) of treated but none of the control patients became HBeAg-negative between completion of therapy and 12 months. Reactivation of HBV replication subsequently occurred in 7 (13%) of the treated patients and in 1 control. Thus, sustained clearance of HBeAg was achieved only in 8 (15%) of treated patients at 12 months. Between 12 and 24 months 3 (9%) of treated patients and 1 control became negative for HBeAg. None of the patients became HBsAg-negative. alpha 2-interferon in the dose regimen used has little long-term effect in the suppression of HBV replication in Chinese patients with chronic HBV infection.