We compared all frozen section examination of ovarian tumors during a 5 year period in our institute with permanent section diagnosis from paraffin sections. In this period, 604 ovarian tumors had frozen section examination. Final histologic diagnosis was divided into benign, low malignant potential and malignant. Sensitivity of frozen section diagnosis for malignant was 80 %, low malignant potential 73,1%, and benign 99.8%. Predictive value for malignancy was 98.5%, for low malignant potential 76.6%, and for benign disease 96.2%. Diagnostic problems occurred in huge tumors and low malignat potential mucinous tumors. Analysis of the 32 false negative(miss or under diagnosis) revealed that a sampling error was involved almostly. The cases of discrepancy between frozen section diagnosis and permanent section diagnosis, were 26/34 in mucinous tumors and 33/34 in huge size of tumors(more than 10cm). Although surgeons and pathologist are aware of the limitations of frozen section diagnosis of ovarian tumors, peroperative histologic examination can be worthwhile and prevent under or over treatment of ovarian malignancies.