The efficacy of immunosuppressive treatment was evaluated in a group of 15 children (aged 2-10 years) affected by clinically asymptomatic, biochemically mild, HBSAg-positive, delta-antibody-negative, histologically moderate, chronic active hepatitis (CAH). Clinical, biochemical, serological, and histological features of chronic hepatitis B virus (HBV) infection were studied during a follow-up of 2 years. Eight of 15 patients received immunosuppressive treatment (prednisone plus azathioprine); seven received a placebo. No significant differences were found among treated and untreated patients, an overall improvement of nearly all parameters of disease (aminotransferases, albumin, prothrombin time, immunoglobulins, bromsulphalein at 45 min, and bile acid serum levels) being found in both groups. Treated patients showed an improvement in aminotransferase levels only at the first 3-month checkup. This finding, however, was not statistically significant in our study and disappeared at subsequent follow-up examinations. A high incidence of HBeAg was noted at entry into the study (10 of 15 patients checked). HBeAg seroconversion was observed in two of the six HBeAg-positive treated patients and in two of the four HBeAg-positive untreated patients. Finally, the histological picture showed similar patterns in both groups of patients studied. Our data suggest that no benefit from immunosuppressive therapy can be proven at this time in asymptomatic, moderately active, HBsAg-positive, delta-negative CAH in children.