Objectives: To find the Risk of malignancy index 4 among women with ovarian masses and to evaluate its ability to discriminate benign mass from a malignant mass. Methods: It is a prospective study including 30 random women with ovarian masses attending OPD and emergency of department of Obstetrics and gynaecology, Index Medical College and Hospital Indore. After obtaining informed consent from all patients, a full history was obtained and a general and gynaecology examination was performed. Results: The p-value of RMI 4 for differentiating benign and malignant tumor for serous and mucinous histology was less than 0.05 which indicated significant correlation. But for other histologies, the p-value was more than 0.05 which indicated non-significant correlation. Conclusion: RMI 4 is a reliable tool for differentiating benign and malignant tumors. It is a simple, reliable and applicable method in the primary evaluation of patients with ovarian masses