The objective of the study was to determine the clinical and immunological characteristics of primary Sjogren's syndrome (SS) in patients with an older onset of the disease. We included 223 consecutive patients (204 female and 19 male; mean age at onset 53 years; range 15-87 years) visited in our Units. All patients were white and fulfilled four or more of the diagnostic criteria for SS proposed by the European Community Study Group in 1993. Disease onset was determined on the basis of the appearance of symptoms strongly suggestive of SS. In 31 patients the onset of disease occurred after the age of 70 years, and they represent the elderly-onset group described in this report. The remaining 192 patients presented disease onset before the age of 70 years, and they represent the younger-onset group. Of the 31 (14%) patients with elderly onset of primary SS, 26 were female and 5 male, and the disease onset occurred between 70 and 87 years (mean 74 years). The most common extraglandular manifestations were articular involvement (29%), hepatic involvement (20%), peripheral neuropathy (16%) and interstitial pneumopathy (13%). When compared with patients with a younger onset, the prevalences of glandular and extraglandular manifestations and immunological features (cryoglobulinemia, hypocomplementemia and positivity for RF, anti-Ro/SS-A or anti-La/SS-B) were similar in both groups. In conclusion, although primary SS is typically a disease of middle-aged adults, clinicians should note that it may be diagnosed frequently among elderly patients. However, we could not find any notable differences in clinical and immunological characteristics of patients with elderly onset of primary SS.