Unstimulated whole saliva collection (U.W.S.C.) and stimulated parotid flow rate (S.P.F.R.) are routine tests for evaluation of xerostomia. Different groups of investigators, however, use different normal values; some prefer one test (either one) more than the other. This prompted us to evaluate these tests in 81 well documented primary Sjögren's syndrome (prim. SS) patients and 188 age and sex matched normal volunteers. The U.W.S.C. as well as the S.P.F.R. were performed for 5 min. Lemon juice was used for stimulation and the saliva from the parotid gland was collected using modified Carlson-Crittenden cups. Normal individuals produced from between 0.20 and 6.81 ml/5 min (x +/- SD: 2.03 +/- 1.36 ml) of U.W.S. and from between 0.00 and 7.50 ml/5 min (x +/- SD: 1.00 +/- 1.10 ml) of S.P.F. No statistical differences were observed between the two salivary flow rates. Primary Sjögren's syndrome patients produced from 0.04 to 2.00 ml/5 min (x +/- SD: 0.47 +/- 0.50 ml) of U.W.S. and from 0.00 to 2.00 ml/5 min (x +/- SD: 0.37 +/- 0.56 ml) of S.P.F. Using the 95% confidence limit of the flow rates (U.W.S.: 1.25 ml/5 min and S.F.P.: 1.5 ml/5 min) observed in prim. SS patients, it was observed that 57% of the U.W.S. and 78% of the S.P.F values produced from normal individuals fall into that range. Based on these findings we conclude that these two tests are not useful for the evaluation of xerostomia.