We determined the serum angiotensin converting enzyme and lysozyme levels in 221 patients with uveitis and in 67 control subjects. Angiotensin converting enzyme and lysozyme levels were found to be age dependent. Of the 221 patients, 12 had sarcoidosis. In patients with uveitis who had an angiotensin converting enzyme level above 50 units/l (mean + 2 S.D.), the sensitivity of the test was 84%, the specificity was 95%, and the predictive value was 47%. In these same patients the sensitivity was 60% for a lysozyme level above 8 mg/l (mean + 2 S.D.), the specificity was 76%, and the predictive value was 12%.