Clinical, histologic, and immunohistochemical studies were performed in 11 patients suffering from sicca syndrome with extraglandular lymphoid lesions (liver, spleen, lymph nodes and bone). Seven patients proved to have primary Sjögren's syndrome (SS), 3 had non Hodgkin's lymphoma (NHL) with glandular and extraglandular monoclonal B-cell infiltrates, and 1 had diffuse Castleman's disease (CD). Antibodies to nuclear and/or cytoplasmic ribonucleoproteins were found, by immunodiffusion, in sera from all patients with SS (anti-SSA/Ro in 7 cases and anti-SSB/La in 6). No patient with NHL or CD had evidence of circulating antibodies to these antigens as well as other soluble nuclear antigens. Our data suggests that antibodies to SSA/Ro and SSB/la are strongly associated with extraglandular lymphoid lesions in primary SS and may be useful in differentiating this condition from sicca complex with NHL.