β(2)-microglobulin is normally present in low concentrations in serum and other bodily fluids. By use of a radioimmunoassay, we measured salivary and serum β(2)-microglbulin concentrations in 40 patients with Sjogren's syndrome. The β(2)-microglobulin was significantly elevated in the saliva of patients with Sjogren's syndrome (p<0.005), but not in the serum. It was also elevated in the saliva of patients who had severe inflammatory change in the minor salivary gland, abnormal sialographic findings, reduced salivary flow rate and anti SS-A or SS-B antibody in their sera. There was no relation between the salivary , β(2)-microglobulin concentrations and the presence of various autoimmune diseases associated with Sjogren's syndrome. Measurement of salivary β(2)-microglobulin may offer a simple method of quantifying local activity in Sjogren's syndrome.