During breast conserving surgery (lumpectomy) procedures, the status (positive, close, negative) of the surgical tumor margin is the most important factor for determining local recurrence. Too often, repeat surgeries are required for complete resection. Margin status is currently assessed microscopically using postoperative histopathology, with limited sampling of visually suspicious areas. In this report, the authors perform intraoperative optical coherence tomography (OCT) for the real-time point-of-care microscopic assessment of surgical margins during lumpectomy procedures. From a study involving 37 patients, comprising training and study groups, a sensitivity of 100% and a specificity of 82% was found for determining margin status using intraoperative OCT, compared to standard postoperative histopathology. Positive and close margins were identified by the presence and pattern of dense, high-scattering regions, indicative of tumor cells, compared to lowscattering adipocytes from negative margins. These results suggest the future use of OCT as an intraoperative imaging modality for the comprehensive real-time microscopic assessment of tumor margins, which offers the potential to increase the microscopic sampling and visualization of the tissue, and significantly reduce reoperation rates. The cover shows a series of OCT images acquired across a three-dimensional surgical margin that is positive for tumor. Identified regions of tumor cells along the surgical margin appear as bright yellow. For details, see the article by Nguyen and colleagues on page 8790 of this issue.