The prevalence of musculoskeletal complaints suggestive of the fibromyalgia syndrome (FS) was evaluated in 30 patients with primary Sjögren's syndrome (1 degree SS) and in two control groups of patients with osteoarthritis (OA) and diabetes mellitus (DM). In addition, the presence of depressive state was investigated in patients and controls using the Hamilton rating scale and an Italian self-evaluating test. Fibromyalgia features were found in 14 1 degree SS patients (47%), in 21 OA (70%) and in 10 DM (33%) controls. 1 degree SS patients showed the highest prevalence (47%) of moderate-severe depression with respect to OA (20%) and DM (7%) groups (p less than 0.01). Furthermore, while FS features correlated closely with both tests for depression in 1 degree SS (p less than 0.001), this correspondence was absent or much less significant in the other disease groups. Finally, neither psychopathological features nor FS complaints appeared to be related to the other clinical and serological findings of 1 degree SS.