In studies reported recently, the sera of patients with Sjögren's syndrome were found to contain precipitating antibodies to nuclear antigens that can be identified by immunodiffusion analysis. These precipitating autoantibodies have been termed SS-A and SS-B antibodies. We show that identification of these autoantibodies helped in establishing the diagnosis of Sjögren's syndrome in 12 of 30 patients in whom the diagnosis had not been considered at the time of the physician's initial examination. The reasons for this were related to lack of spontaneous complaints of keratoconjunctivitis sicca and xerostomia and prominence of symptoms associated with arthritis, myalgia, pulmonary fibrosis, and cardiac disease. This study re-emphasizes the importance of multisystem disease in Sjögren's syndrome and shows that specific serologic assays for autoantibodies aided in diagnosis.