Patients with pelvic mass, especially ovarian masses are commonly encountered in gynaecology clinic and this can be either benign or malignant. There is no single method which canaccurately predict ovarian malignancy. Prompt identification of ovarian malignancies and referralto a gynec-oncologist can enhance the patient survival rates. Aim of this descriptive analytical study is to evaluate the Diagnostic accuracy of the Risk of Malignancy Indices (RMI) in discriminating benign and malignant ovarian masses. Patients operated for ovarian masses between January 2017 and December 2017 were included in the study. Data regarding menopausal status, ultrasound findings, serum CA125 level and post op pathology findings were collected and analysed. A score was assigned for ultrasound findings as follows:the presence of multilocular cystic lesions, solid areas, bilateral lesions, ascites and intra-abdominal metastases, scored one point each. A total ultrasound score (U-score) was calculated for each patient. Postmenopausal status was defined as more than one year of amenorrhea, or an age of 50 years or more if the woman had undergone hysterectomy. All other women were considered to be premenopausal. RMI1, RMI 2, RMI 3, RMI 4 were calculated for all patients together with the sensitivity, specificity, positive and negative predictive values of the four methods. RMI 1 = U × M × serum CA125, where a total ultrasound score of 0 gave U = 0, a score of 1 gave U = 1 and a score of > 2 gave U = 3; premenopausal status gave M = 1, postmenopausal M = 3. The serum level of CA125 was multiplied directly into the formula. RMI 2 = U × M × serum CA125, where a total ultrasound score of 0 or 1 gave U = 1 and a score of > 2 gave U = 4;