There is a paucity of information concerning the frequency of malignant parovarian tumors and how to diagnose them preoperatively. Our retrospective 10-year analysis showed that among 168 women with parovarian tumors, three had malignancy (2%). Our data and a literature review suggest that most malignancies occur in reproductive-age women with cysts over 5 cm containing internal papillary excrescences. It remains to be determined what the roles of ultrasound and cytology are in diagnosing malignancy.