The accuracy of frozen section diagnosis in the intraoperative evaluation of ovarian masses is very importantwith regard to surgeon selection of appropriated operating procedures. For evaluation in our institute, therecords of 127 patients with ovarian masses submitted for intraoperative frozen sections between January 2001and December 2005 were reviewed. After exclusion of 4 completely infarcted masses and 11 cases with deferredfrozen section diagnoses, 112 were analyzed for diagnostic accuracy by comparing with the final histologicresults. We found sensitivity in the diagnosis of benign, borderline and malignant tumors to be 100%, 84%, and92 %, respectively, with specificities of 92.7%, 97.9%, and 100%, respectively. The overall accuracy with frozensections was 94 %. Among 18 patients with deferred or discordant diagnoses, mucinous tumors accounted for72 % of cases. No over-diagnosis of malignancy or misdiagnosis of metastatic lesions as primary ovarian cancerby frozen sections was observed. In conclusion, the accuracy of intraoperative frozen section for the diagnosisof ovarian masses is high. Frozen sections also help in the evaluation of metastatic tumors to the ovary. Mucinoustumors constitute an important group causing diagnostic discrepancies.