127 Background: Inadequate lumpectomy margins are associated with an increased risk of ipsilateral recurrence in patients undergoing breast conserving surgery for cancer. Multiple procedures are often required to achieve acceptable margins, increasing the burden to the patient and the health care system, and potentially delaying other adjuvant treatments. A novel device for intraoperative assessment of lumpectomy margins (MarginProbe) has been associated with a 25% reduction in the rate of positive margins at the conclusion of primary lumpectomy surgery. Our aim was to establish a baseline re-excision rate among surgeons and to initiate a follow up study to assess the impact of incorporating this new technology for intraoperative margin assessment. Methods: The NYU Langone Medical Center Breast Cancer Database was queried for patients who underwent breast conserving surgery including ≥ 1 re-excision procedure from 1/2010-1/2013. Variables of interest included re-excision rates, stage of disease, and additional margins taken at primary lumpectomy surgery. Statistical analyses included descriptive analyses and Pearson’s Chi-Square. Results: During the study period 957 patients had breast conserving surgery and 229 required ≥ 1 re-excision procedures (24%). Re-excision rates varied widely among surgeons (10-36%). Stage 0 disease (ductal carcinoma in situ) was associated with an increased frequency of re-excisions (p<0.0001). These parameters will be re-evaluated in patients undergoing breast conserving surgery with adjunctive intraoperative use of the MarginProbe device. Re-excision rates and the accuracy of intraoperative assessment of lumpectomy margins will be compared with the historical cohort. Conclusions: The necessity for multiple surgical procedures to complete breast conserving surgery results in an added burden to the patient and the health care system. Improved intraoperative assessment of lumpectomy margins represents an opportunity to improve the quality of breast cancer surgery. A critical analysis of the impact of a new device on re-excision rates will be important to understand its potential benefit to the conduct of breast conserving surgery.