This report will discuss a case of carcinoid tumor arising in a mature cystic teratoma in a 27-year-old single nulligravid, who initially consulted for primary amenorrhea and right lower quadrant pain. Pelvic ultrasound was done and revealed an ovarian cyst on the right, to consider mature cystic teratoma. She underwent right oophorectomy with unremarkable post-operative course. Furthermore, this case report will tackle the diagnosis, definitive management and prognosis of the condition.