BACKGROUND Sjögren's syndrome (SS) is a chronic autoimmune disorder, with its major clinical manifestations resulting from changes in exocrine glands. OBJECTIVE The aim of this study was to evaluate serum concentrations of circulating immune complexes (CIC) and immunoglobulin G (IgG), and salivary proteins (SP) and salivary immunoglobulin A (slgA) in 40 patients with SS, and to correlate these values among themselves, as well as with the unstimulated salivary flow rate (USFR) and the duration of disease. METHODS The total of 40 patients were included in this research. CIC was determined using the solution of polyethylene glycol and IgG with the standard procedure of radial immunodiffusion. SP was investigated by the method of Lowry and slgA was separated from the whole saliva using the method of immune chromatography. RESULTS The values of most of the studied parameters exceeded the normal range in a high degree: CIC 72.5%, IgG 70%, SP 80%. The concentrations of CIC were significantly higher in the patients with the duration of disease less than 10 years. With the decrease of USFR, the concentration of slgA and IgG were increased with statistical significance. CONCLUSIONS The increased prevalence of abnormal values of CIC, IgG and SP indicate that the patients with SS have developed a higher level of immune reactivity. These results could be useful in diagnosis and disease activity monitoring.