Objective To study the diagnostic value of pleural effusion combined with serum adenosine deaminase(ADA),carcinoemhryonic antigen(CEA)in testing tuberculous and malignant pleural exudates.Methods Diagnostic kit for carcinoe mbryonic antigen(CEA)and ADA measured by ELISA and Enzyme continuotrs monitoring method was examined among 91 patients with pleural exudates.Results The ADA activity of tuberculous and malignant exudates were respectively(42.32±17.56)U/L and(10.29 4-6.34)U/L(P<0.01).If the critical value of ADA was larger than 40U/L in tuberculous diagnosis,its sensitivity Was 82.5%and the specificity was92.2%as the critical value of ADA mole than 40U/L.its sensitivity was 92.5%and the specificity Wag 90.2%as the critical value of PADA/SADA more than 1.The CEA activity of tuberculous and malignant exudates were respectively(8.314±3.62)ug/L and (24.7±1 3.6)ug/L(P<O.01).If the critical value of CEA was larger than 20ug/L in malignant pleural exudates,its sensitivity was 58.8%and specificity was 95.0%.If the critical value of PCEA/SCEA was larger than 1 in malignant pleural exudates,its sensitivity was 86.3%and the specificity was 92.5%.Conelusion The test of ADA and CEA of pleural exudates is of great diagnostic value in patients with tubeleulous and malignant pleural effusion. Key words: Adenosine deaminase(ADA); Carcinoembryonic antigen(CEA); Tuberculous pleural effusion:Malignant pleural effusion