Immunogenicity of 14 valent pneumococcal vaccine was evaluated in a placebo controlled, double blind, randomized study involving 77 patients with systemic lupus erythematosus (SLE). Antibodies to 12 type specific capsular antigens were measured prior to and one and 6 months post injection. In 17 patients treated with prednisone plus cyclophosphamide and/or azathioprine, mean body concentrations (ng antibody nitrogen/ml serum) increased from 528 to 1328 and 852, respectively, in vaccinated patients compared to 307, 308 and 344 following placebo. In 60 patients not receiving immunosuppressives, mean antibody concentrations were 355, 1361 and 920 post vaccine and 401, 473 and 377 post placebo. Our study demonstrates that antibody responses to pneumococcal vaccine in SLE patients is unaffected by these immunosuppressive agents.