Serum immunoglobulins were measured in 107 patients with human immunodeficiency virus seropositivity. Each patient was categorized by the Walter Reed staging classification and serum concentrations of immunoglobulins were compared with patient staging. Serum IgM concentrations were normal in all but nine patients. Serum IgG concentrations were elevated in 74 of 107 patients, with no significant differences noted between different stages of disease severity. Serum IgA concentrations were elevated in 38 of 107 patients, with a significant relationship noted between increasing staging category and increasing serum IgA concentration (p = 0.0001). Serum IgA concentrations in patients with human immunodeficiency virus seropositivity may be a useful marker of immunologic progression of disease.