Sialochemistry was performed on the stimulated parotid secretion of a group of patients with Sjögren's syndrome (SS) having a Grade 4 lymphocytic infiltrate of their minor labial salivary glands and a normal control group. Parameters examined included flow rate, and concentration of sodium, potassium, chloride, urea, calcium, phosphate, total protein, IgA, IgG. albumin, amylase and lactoferrin. Although all SS patients had virtually no parotid secretion in the absence of stimulation, with a gustatory stimulation, 40% of the patients with SS had a relatively normal parotid flow rate, when compared with the control group. The SS patients, regardless of flow rate, exhibited a highly significant (p less than 0.01) elevation in the concentration of sodium, chloride, IgA, IgG, and lactoferrin and a significant (p less than 0.05) increase in albumin concentration, when compared with the control group. The phosphate level was significantly lower (p less than 0.01) in SS patients than in the control group. The elevated IgA in SS was almost all 11S, in contrast to parotitis where 7S was a major contributor. In view of the variation in flow rate in SS patients chemical quantitation of selected salivary components can be a valuable aid in the differential diagnosis of this disease and in monitoring patients over time.