The lysozyme test is the most sensitive test for the diagnosis of the sicca syndrome. The agar diffusion method could be used as a routine diagnostic procedure. With a diameter limit of 21½ mm of lysis under the test conditions described, one out of every 100 diagnoses would be wrong. For the rose bengal test, using a limit of score of staining intensity of 3½ one out of every 20 to 25 times a diagnostic error could be expected. With the Schirmer's 1 test, using a limit of 5½ mm wetting the filter-paper strip, one out of every six persons would be misclassified. No difference in values between men and women was found at any age level in any test. Age effects were found with lysozyme and Schirmer's 1 tests, but not with the rose bengal test.