• Suppressor T-cell function was analyzed in seven children with acquired autoimmunodeficiency syndrome (AIDS) or AIDS-related complex (ARC). Four of the patients had markedly increased serum IgG levels. All patients had elevated percentages and absolute numbers of peripheral blood T8 cells. In vitro concanavalin A generation of suppressor cells for T-cell mitogenic responses and suppression of pokeweed mitogendriven immunoglobulin secretion were diminished in all patients. After intravenous treatment with gamma globulin, four patients regained in vitro suppression of pokeweed mitogen-driven gamma globulin secretion. Treatment with intravenous gamma globulin also modified in vitro suppressor T-cell functions in children with AIDS or ARC.