Abstract: ObjectiveTo investigate the diagnosis value of tumor markers (CYFRA21-1, CEA, NSE and CA153) in malignant pleural effusions. Methods 108 cases with malignant pleural effusions and 90 cases with benign pleural effusions were detected by radio immunoassay and ELISA, and then the results were compared. Results The four item of cancerous pleural effusion group were markedly higher than those of the benign ones(P<0.01).The sensitivity, specificity and accuracy rating of the combined detection of targets for diagnostician malignant pleural effusion were markedly higher. Conclusion The combined detection of CYFRA21 -1，CEA，NSE and CA153 has specific value in the diagnosis for malignant pleural effusions.