The mesothelial cysts of the round ligament of uterus are rare. They are misdiagnosed as ovarian/ para ovarian cysts, inguinal hernias, abscess. We report a case of 48-years-old female with gradual painless distension of abdomen. Up on explorative laparotomy cyst was seen arising from right round ligament. Excision of cystic mass was done and pathologically confirmed mesothelial cyst. Establishing accurate per operative diagnosis based on clinical findings before surgery is very important and challenging. Ultrasound and computerized tomography (CT) scan are the imaging modalities used for diagnosis, but these may not be able to differentiate an ovarian cyst from round ligament mesothelial cyst.