Aim: The aim of this study was to determine the diagnostic value of thrombocytosis and high CA 125 levels in women with benign and malign adnexal masses. Thrombocytosis (platelet counts >400 × 10(9)/l) has been identified as a poor prognostic factor in many cancers including certain gynecologic malignant tumors such as endometrial, cervical, and ovarian cancers. Methods: Medical charts of 180 patients with adnexal masses were retrospectively reviewed and analyzed for the association of preoperative thrombocytosis and high CA 125 level with other clinical prognostic factors. Results: Of the 180 participants, 68 (68% of malignant adnexal masses) had thrombocytosis and 74 patients (74% of malignant adnexal masses) had elevated CA 125 levels. The patients with preoperative thrombocytosis were found to have greater elevations of CA 125 levels, more advanced stage disease, and higher grade tumors. Conclusion: Presence of thrombocytosis and high CA 125 alone and in combination may be used as a prognostic factor in the management of women with adnexal masses since they are already used as clinical tests for several purposes.