Thirty-six children with chronic hepatitis B were entered into a randomized controlled trial of recombinant human interferon-alpha. All patients had hepatitis B virus DNA and increased levels of aminotransferases in serum for at least 1 yr. Twelve children received 10 MU of interferon-alpha 2b/m2 body surface area three times a week (group I); 12 children received 5 MU/m2 under the same conditions (group II); and 12 children served as controls (group III). During 6 mo of therapy, 12 of 24 (50%) treated patients (7 from group I, 58%, and 5 from group II, 42%) and 2 of 12 (17%) controls lost hepatitis B virus DNA from serum and subsequently remained negative. Comparison of the rate of response in group I vs. controls showed a statistically significant difference (p less than 0.05). Eleven of 12 (92%) treated patients who cleared hepatitis B virus DNA from serum lost HBeAg, seroconverted to anti-HBe and had improvement in liver histological findings with loss of hepatitis B virus DNA from liver. In 10, serum ALT levels became normal. Interferon-alpha was well tolerated and all children finished therapy. These findings indicate that a 6-mo course of interferon-alpha is effective in inducing a serological, biochemical and histological remission of disease in approximately 50% of children with chronic hepatitis B.