Introduction : Ovarían cysts are cystic neoplasms derived from ovarian tissue, can be benign or malignant. Characteristics ofovarian cysts is importantto be known, such as body mass index and risk ofmaligriancy index. Not only to be able to assess risk factors but also early detection prompt treatment to prevent progression to ovarian cancer.Methods : This is a descriptive study, conducted in Department of Obstetrics and Gynecology Hospital, Adam Malik Medan Medical records from all patients who will undergo elective surgery for ovarian cysts from January Pt 2010 to December 31th 2012 was collected. Data was analyzed descriptively and analytically with chi square by level of significance in this study was p 35 U/ml (95.8%), and the RMI > 250 (88.9%). Majority of patients with benign ovarian cysts aged 31-40 year olds (28.3%), parity 2-5 (46.5%), menarche at 13-16 years old (85.4%), BMI obese (44.9%), CA 125 levels similar, and RML 250 (63.8%). The most common ovarian cyst is malignant adenocarcinoma (72 patients, 36.2%). This study showed that BMI (p=O.OO8) and RMI (jsO.OO1 ) are associated with ovarian cyst. Conclusion: This study showed that there is association of body mass index and risk of malignancy index with ovarian cysts. Need further research with larger population samples. Keywords : Ovarían cysts; Body Mass Index; Risk of Malignancy index