Purpose of investigation: To distinguish adnexal masses as benign and malignant, and to thereby identify the suitable surgical method for these masses, in premenopausal women, by retrospectively evaluating over a ten-year period, the diagnostic parameters, such as serum CA 125 and transvaginal ultrasonography (TVS), in combination with the presence of ascites in the abdomen. Materials and Methods: The study was conducted with 255 premenopausal patients diagnosed with adnexal masses who had been admitted to the Gaziantep University Faculty of Medicine, Clinic of Gynecology and Obstetrics, between January 2003 and January 2013. Data collected from these patients included age, menopausal state, information regarding the presence of ascites, ultrasound findings, and serum CA 125 levels. Results: The mean age of the women included in the study was 32.79 +/- 8.11 (range: 18-51) years. Based on the criteria mentioned above, 152 patients were treated by laparoscopy based on a strong suspicion of benign mass, while 103 patients were treated by laparotomy, based on a strong suspicion of malignant mass. CA 125 values did not have a significant effect on malignancy risk. Based on the TVS results, three malignant masses were reported postoperatively in the patient group strongly suspected to have benign masses, while five benign masses were reported postoperatively in the patient group strongly suspected to have malignant masses.An evaluation of the present diagnostic method showed that the TVS has a positive predictive value (PPV) of 94.19% in identifying malignant masses, and a negative predictive value (NPV) of 98.22% in identifying benign masses. Conclusion: TVS and CA 125, along with an evaluation of menopausal status and ascites, can be an effective approach for diagnosing adnexal masses, and also for determining the proper surgical method to follow.