The aim of this study was to investigate the diagnostic role of the CA 125, ferritin, beta-2 microglobulin (β2 M), and lactic dehydrogenase (LDH) levels in serum and peritoneal fluid (PF) in patients with ovarian neoplasms. Using cross-sectional study design; serum and PF CA 125, ferritin, β2 M, and LDH levels were analyzed in 40 patients with benign ovarian neoplasms (Group 1) and 59 patients with malignant ovarian neoplasms (Group 2) which were evaluated surgically. Serum and PF levels of these markers compared between the groups. Diagnostic role of these markers were determined with receiver operating curve (ROC) analysis. Serum and PF CA 125, ferritin, β2 M, and LDH levels were statistically significant higher in patients with ovarian cancers as compared with benign neoplasms. Among these biomarkers, PF β2 M levels had highest sensitivity and specificity, 76.3 and 85%, respectively with the cut-off value: 2.3 mg/l. This study results indicates that especially PF β2 M and ferritin levels may be valuable for diagnosis of malignant ascites in patients with ovarian neoplasms.