Ninety Chinese hepatitis B surface antigen (HBsAg) carrier children, aged 2-17 years, positive for hepatitis B e antigen (HBeAg) and hepatitis B virus DNA on at least three occasions in 6 months, were randomized into 3 groups. Thirty children received syrup vitamin B complex as control, 29 received 6 weeks of placebo syrup followed by 16 weeks of recombinant alpha 2b-interferon [intron A (rIFN2b)], 5 x 10(6) u/m2 subcutaneously thrice weekly; and 31 received 6 weeks of syrup prednisone (0.6 mg/kg tailed to 0.2 mg/kg) followed by 16 weeks of recombinant alpha 2b-interferon as above. The placebo/prednisone syrup was given on a double-blind basis. At 24 months of follow-up, persistent loss of hepatitis B virus DNA occurred in none of the children in the control group, in one child receiving recombinant alpha 2b-interferon alone, who also seroconverted to anti-HBe and anti-HBs and in five children receiving interferon with steroid priming (p = 0.0571 compared with controls), with four seroconverting to anti-HBe and one also seroconverting to anti-HBs. A rise of transaminases to above twice the upper limit of normal levels during the first 7 months of follow-up occurred in one subject in the control group, four in the group receiving alpha 2b-interferon alone and nine in the group receiving recombinant alpha 2b-interferon with steroid priming (p = 0.0144 compared with controls). Side effects of the steroid were negligible; those of recombinant alpha 2b-interferon were transient and acceptable. We conclude that 6 weeks of prednisone followed by 16 weeks of recombinant alpha 2b-interferon is of use in inducing persistent loss of hepatitis B virus DNA (16.1 per cent) and e-seroconversion (12.9 per cent) in a proportion of Chinese HBsAg carrier children: the prednisone probably enhances the immunomodulatory effect of recombinant alpha 2b-interferon.