Papular acrodermatitis of childhood (PAC) is characterized by papular eruption of skin, lymphadenopathy, and acute hepatitis B surface antigen (HBsAg)-positive anicteric hepatitis. To study the course of hepatitis B virus infection we followed 16 patients with PAC, 2 to 7 years of age, for periods ranging from 6 to 46 months. All patients tested developed hepatitis B surface antigenemia subtype ay, and produced antibody to hepatitis B core antigen with the highest incidence after 3 to 5 months. Half of the children investigated developed antibody to hepatitis B surface antigen 4 to 18 months (mean, 6.5) after the onset of PAC. At the end of the investigation, 31% of the children were still HBsAg-positive, 50% were antibody to hepatitis B core antigen-positive, and in 43% the activity of serum aminotransferases was abnormal. Liver biopsy repeated in 2 children showed chronic aggressive hepatitis. The pattern of antibody response to hepatitis B virus is similar in both HBsAg-positive hepatitis and PAC. The frequent development of HBSAg carrier state and the high proportion of children with liver abnormalities at the end of the investigation suggest an impaired clearance of hepatitis B virus and a tendency to chronicity.