In order to investigate the clinical value of vascular endothelial growth factor (VEGF) combined with interferon-γ (IFN-γ) in diagnosing malignant pleural effusion and tuberculous plearal effusion, 42 cases of malignant pleurai effusion and 45 cases of tuberculous plcural effusion in Tongji Hospital, from March 2004 to May 2005, were included. The carcinoembryonic antigen (CEA), VEGF and IFN-γ levels of pleural effusion were detected by using ELISA, and adenosine deaminasc (ADA) activity was determined by using enzyme kinetic analytical method. The sensitivity, specific-ity, accuracy and area under the curve (AUCROC) of CEA and VEGF, VEGF/IFN-γ ratio, ADA and IFN-γ were measured by receiver operating characteristic curve (ROC). The results showed that CEA, VEGF levels and VEGF/IFN-γ ratio were significantly higher and the ADA and IFN-γ levels were significantly lower in malignant group than those in tuberculous group (P