A seroimmunologic evaluation of 57 children with chronic hepatitis is presented. Twenty-one patients had chronic persistent hepatitis and 36 had chronic active hepatitis. Serum samples obtained before treatment were tested for HBsAg, anti-HBs, anti-HBc, smooth muscle antibody, and antibody to endoplasmic reticulum. A persistently positive HBsAg was observed in the serum of 18 of the 21 patients with chronic persistent hepatitis. The chronic active hepatitis group was divided into three subgroups according to the presence of hepatitis B-virus markers (7 patients), smooth muscle antibody (10 patients), and endoplasmic reticulum antibody (9 patients). Determination of these markers could be useful for classifying children with chronic hepatitis.