Lymphangioma of the ovary is very rare, with only 17 cases reported to date. In this report, a 43-year-old woman with lymphangioma of the ovary accompanied by chylous ascites is described. Vaginal ultrasound showed a solid cystic tumor at the right ovary accompanied by ascites. The volume of ascites was changeable. Milky fluid obtained by Douglas pouch aspiration contained numerous mature lymphocytes. She underwent right salpingo-oophorectomy. Histological examination revealed that the excised tumor from the right ovary was consistent with benign lymphangioma. This is the first case report of lymphangioma of the ovary accompanied by chylous ascites. We should discriminate such cases from other malignant tumors in order to avoid overtreatment.