Objective: To determine the relation between the levels of cell free DNA in plasma of benign and malignant ovarian tumors. Study design: Prospective cross sectional study including 50 women divided into 2groups, group A includes 20 women with ovarian malignancy, group B includes 30 women with benign ovarian lesions diagnosed after clinical and histopathological examinations. Venous blood samples were taken from all patients. PCR using β-globin detection was used to quantify cffDNA in plasma. Results: preoperative cell-free DNA levels are significantly elevated in patients with ovarian carcinoma when compared with individuals with benign ovarian disease (P<0.000). Conclusion: preoperative cell-free DNA levels are significantly elevated in patients with ovarian malignancy when compared with individuals with benign ovarian disease so can be used as diagnostic biomarker.