Introduction. The diagnosis of malignant ascites is a challenging problem in clinical practice, non-invasive techniques should be developed to improve diagnostic accuracy. The diagnostic performances of tumor markers in malignant ascites remained unsettled. Our aim was to evaluate diagnostic performance of tumor markers in differential diagnosis of benign and malignant ascites. Material and methods. A total of 437 patients were enrolled, and the relevant parameters of the patients were analyzed for the differentiation of benign ascites from malignant ascites. Results. At the predetermined cutoff values of tumor makers, tumor markers in ascitic fluid showed better diagnostic performance than those in serum. Combined use of tumor markers and the cytology increased the diagnostic yield of the latter by 37%. In cytologically negative malignant ascites, tumor markers provided assistance in differentiating malignant ascites from benign ascites, and the combination of ascitic tumor markers yielded 86% sensitivity, 97% specificity. Conclusion. Use of a panel of tumor markers exhibited excellent diagnostic performance in diagnosing malignant ascites, which indicated the detection of tumor markers may represent a beneficial adjunct to cytology, thus guiding the selection of patients who might benefit from further invasive procedures.