Prednisone is used to treat a number of complications of the human immunodeficiency virus (HIV) infection, but there is little information about the immunologic consequences of such therapy. We gave prednisone to six boys with hemophilia who were infected with HIV in order to study its effects on their clinical status, serum immunoglobulins, lymphocyte populations, and serum HIV antigen concentrations. Most patients had clinical improvement while taking prednisone; platelet counts increased in five, weight increased in four, and adenopathy abated in two patients during the study. Serum IgG concentrations declined in all patients, but there were no significant changes in serum IgA or IgM concentrations. There was no consistent or significant change in the number of percentage of CD3, CD4, CD8, or CD19 lymphocytes. HIV antigen was present in the serum of one patient, and its concentration did not change during the study. None of the patients became HIV antigen seropositive during the study. These results indicate that prednisone administration was associated with clinical improvement without deleterious immunologic effects when given to children with HIV infection.