Purpose: To compare the diagnostic accuracy of the neutrophil/lymphocyte ratio (NLR) with the platelet/lymphocyte ratio (PLR) in predicting malignancy of pelvic masses which are pre-operatively malignant suspicious. Materials and Methods: In this retrospective study we evaluated the clinical features of patients with ovarian masses which had pre-operatively been considered suspicious for malignancy. The patients whose intraoperative frozen sections were malign were classified as the study group, while those who had benign masses were the control group. Data recorded were age of the patient, diameter of the mass, pre-operative serum Ca 125 levels, platelet count, neutrophil/lymphocyte ratio and platelet/lymphocyte ratio. Results: There was statistically significantly difference between the groups in terms of age, diameter of the mass, serum Ca 125 levels, platelet number and platelet/lymphocyte ratio. Mean neutrophil/lymphocyte ratios showed no difference between the groups. ROC curve analysis showed that age, serum Ca 125 levels, platelet number and PLR were discriminative markers in predicting malignancy in adnexal masses. Conclusions: According to the current study, serum Ca 125 levels, pre-operative platelet number and PLR may be good prognostic factors, while NLR is an ineffective marker in predicting the malignant characteristics of a pelvic mass.