A prospective, double-blind study was carried out to assess the efficacy of interferon alfa-2b, with or without pre-treatment prednisone withdrawal, in patients with chronic hepatitis B. A total of 57 Belgian and Dutch patients were included in the study. Patients were divided into four treatment groups: Group A, prednisone withdrawal followed by interferon 5 million units per day; Groups B and C, placebo followed by interferon 5 or 1 million units, respectively; and Group D, untreated controls followed for 1 year. All treated patients received interferon for 16 weeks. Two of the 14 control patients lost hepatitis B e antigen during the year of study, and only one of 15 patients in the interferon 1 million units group. Among the 28 patients receiving 5 million units of interferon (with or without prednisone withdrawal), ten (36%) cleared hepatitis B e antigen during the study or within 6 months of the end of therapy. This was associated with a marked improvement in serum transaminase levels. When comparing Groups A and B, it was found that prednisone withdrawal therapy enhanced the response to interferon in patients with pre-treatment serum alanine aminotransferase levels below 100 IU/l, bringing the seroconversion rate up to 50%, compared to 17% on interferon alone. This effect was not seen in patients with high pre-treatment transaminase levels. All treatment responders showed a marked improvement in Knodell index score, whereas in the 15 non-responders from groups A and B, overall inflammatory activity remained the same in six, improved in five and worsened in four.(ABSTRACT TRUNCATED AT 250 WORDS)