Previous studies have found that acute ethanol ingestion before burn injury caused further impairment of mitogenic response of B lymphocytes compared with burn injury alone. The principal role of B lymphocytes is immunoglobulin production. This study was designed to determine the effect of acute ethanol ingestion on circulating immunoglobulin levels before injury. Serum concentrations of IgG, IgM, and IgA in rats were measured with the use of radial immunodiffusion plates at 4 days after a 30% burn injury in animals that had received a single ingestion of 3.0 ml ethanol per kilogram of body weight. The immunoglobulin levels were compared with appropriate controls. A 30% burn injury produced significant decreases in serum IgG and IgA levels but not in IgM levels, whereas acute ethanol ingestion only decreased IgA levels. Acute ethanol ingestion before injury did not induce any further significant decrease than did burn injury alone.