OBJECTIVES Intraoperative frozen section (IFS) offers a rapid test to guide the extent of surgery, which is essential for optimal treatment of ovarian cancer. This study evaluated the diagnostic performance and influence of IFS in the surgical management of ovarian tumors. METHODS A retrospective review was conducted of IFS of adnexal lesions from 2008 to 2013, with diagnoses classified as benign, borderline, or malignant. The diagnostic performance of IFS was calculated, with a focus on primary epithelial tumors. In discordant cases, it was determined whether the results of the IFS influenced the nature of the primary surgery. RESULTS There were 277 consecutive cases over the study period. The overall sensitivity for diagnosing malignant disease was 75.9% and the specificity was 100%. With a benign IFS result, there was a 6.25% (9/144) chance that the final diagnosis would be malignant, and a 7.6% (11/144) chance that the final diagnosis would be borderline, resulting in the potential for understaging. The predictive values for benign, borderline, and malignant IFS results were 86.1%, 66.6%, and 100%, respectively. For a borderline IFS result, there was a 33.3% chance that the final diagnosis would be malignant disease, and this was higher in older patients (53.3%). There were no instances of overdiagnosis in this series. Of 37 cases underdiagnosed, 19 received incomplete primary staging surgery guided by the IFS, and most of these were mucinous tumors. CONCLUSIONS Intraoperative frozen section is most valuable for its high specificity in diagnosing malignancy. It should be interpreted with caution in borderline tumors, particularly in older patients and in mucinous tumors. Overdiagnosis did not occur in this series; however, in younger patients, the limitations of IFS must be considered before surgery that would result in loss of fertility.