A 36-year old Korean woman consulted a clinic for a regular gynecological examination, and a mass was noticed in her pelvis. She was referred to the Asan Medical Center, Seoul where transvaginal ultrasonography confirmed a pelvic mass exceeding 10cm in diameter. She received total abdominal hysterectomy and bilateral salpingoophorectomy, and a borderline serous neoplasm with micropapillary features involving the left ovary and right ovarian serosa was histopathologically confirmed. In addition, a section of a nematode with numerous eggs was found in the parenchyma of the left ovary. The worm had degenerated but the eggs were well-preserved and were identified as those of Enterobius vermicularis. She is an incidentally recognized case of ovarian enterobiasis.