The prevalence of dry eyes or dry mouth, and of primary Sjögren's syndrome (primary SS) according to the Copenhagen criteria were established in 705 randomly selected subjects, aged 52-72 years who answered a simple questionnaire, and of whom 247 (35%) reported symptoms. A subgroup with symptoms (n = 77) and a matched asymptomatic control group (n = 32) were examined with the Schimer-1 test (S1t), tear film break-up time (BUT), van Bijsterveld score (vB), unstimulated whole sialometry (Sialo) and, in about 40% of them labial salivary gland (LSG) biopsy and salivary gland scintigraphy. Apart from four cases of keratoconjunctivitis sicca (KCS) among controls, cases of KCS (15), xerostomia (12), autoimmune sialoadenitis (6) and primary SS (6) were exclusively confined to the symtomatic group. The calculated frequencies (with 95% confidence intervals) for the whole population were 14.9 (7.3-22.6)% for KCS, 5.5(3.0-7.9)% for xerostomia and 2.7 (1.0-4.5)% for autoimmune sialoadenitis and primary SS. The serum levels of ANA and RF were similar in the two groups, though those of anti-SS-B/La antibodies were higher in the group with symptoms (P less than 0.01).