The efficacy of human lymphoblastoid interferon (Wellferon) therapy was measured in 20 children with chronic hepatitis B with or without pretreatment with prednisolone. Patients were randomised to receive 0.6 mg/kg/day prednisolone for 3 weeks, then at 0.3 mg/kg for a fourth week or placebo. All patients then received interferon 5 MU/m2 i.m. for 12 weeks; daily for 5 days then three times a week for the remaining 11 weeks. Preliminary results show that 25% of children had a permanent loss of viral markers of replication. However, response to interferon varied widely between individuals and a prolonged follow-up is required in order to determine the influence of prednisolone pretreatment on the efficacy of interferon therapy.