We reviewed 45 cases of ovarian tUmors treated at Seoul National University Children's Hospital from 1983 to 1993. Forty-five patients were operated upon for 52 ovarian tumors. The most common pathologic diagnosis was mature teratoma. The next were functional cyst, the tumors of epithelial cell origin, and those of stromal origin in order of frequency. Six patients(13%) had malignant tumor. There were one malignant teratoma, two dysgerminomas, one endodermal sinus tumor, and two granulosa cell tumors. Four cases were diagnosed as torsion of ovarian cyst preoperatively, and emergency exploratory laparotomy were performed. There were three cases of ovarian tumors associated with precocious puberty. The most widely used diagnostic tool was ultrasonography.