The aim of the study was to evaluate the safety and effectiveness of interferon alfa-2b, alone and following prednisone withdrawal, in patients with chronic type B hepatitis. Thirty-five patients (27 men and eight women) were randomly allocated to two treatment groups. Group I (n = 17) received 6 weeks of prednisone followed by interferon alfa-2b (INTRON A, Schering-Plough Corporation) 10 million units subcutaneously, three times a week for 16 weeks. Group II (n = 18) was used as an untreated control group for 24 weeks, after which they received 16 weeks of treatment with the same dose of interferon as Group I. Both groups were followed up for 24 weeks after treatment. In Group I, 10/17 patients (58.8%) eliminated hepatitis B e antigen; 8/17 (47.1%) developed antibodies to hepatitis B e antigen; 9/17 (52.9%) became hepatitis B virus DNA negative and 1/17 (5.9%) was hepatitis B surface antigen negative at the end of follow up. In Group II, during the control phase, 1/18 (5.5%) became hepatitis B e antigen negative. When treated with interferon, 7/15 (46.7%) eliminated the e antigen, and 6/15 (40%) developed antibodies to hepatitis B e antigen and were hepatitis B virus DNA negative at the end of follow up. Serum alanine aminotransferase reached normal levels in all seroconverted patients. Liver biopsies showed a marked reduction of inflammation and disappearance of hepatitis B core antigen in liver cell nuclei in almost all cases.(ABSTRACT TRUNCATED AT 250 WORDS)