Although Sjögren's syndrome (SS) is a very common autoimmune disease there are no uniformally accepted diagnostic criteria. In this study we evaluated various clinical parameters as criteria for this disorder. Fifty-two patients with sicca complaints but no evidence of other autoimmune rheumatic disorders were studied. These patients were further subdivided into definite primary SS (primSS) (n = 19) and possible primary SS (n = 33). The patients of the definite group fulfilled 2/3 of the following criteria: xerophthalmia defined by subjective complaints, Schirmer's test less than or equal to 5 mm/5 min or positive rose-bengal staining on slit lamp examination, xerostomia defined by subjective complaints and parotid flow rate less than or equal to 1 cc/5 mm/gland and, presence or history of parotid gland enlargement. In all patients the histology of labial minor salivary glands showed round cell infiltrates greater than or equal to 2+ (Tarpley's classification). The clinical manifestations of definite primary SS were compared to those of patients with possible primary SS. In addition, 49 patients with rheumatoid arthritis (RA) and suspected secondary SS were evaluated. Eleven patients were initially classified as definite secondary SS in association with RA (lip biopsy greater than or equal to 2+ and 1/2 of the criteria: xerophthalmia and xerostomia) and the remaining 38 as possible secondary SS with RA.(ABSTRACT TRUNCATED AT 250 WORDS)