BACKGROUND: Surgical instrument tray reduction attempts to minimize intraoperative inefficiency and processing costs. Previous reduction methods relied on trained observers manually recording instrument use (i.e. human ethnography), and surgeon and/or staff recall, which are imprecise and inherently limited. We aimed to determine the feasibility of radiofrequency identification (RFID)-based intraoperative instrument tracking as an effective means of instrument reduction. METHODS: Instrument trays were tagged with unique RFID tags. A RFID reader tracked instruments passing near RFID antennas during 15 breast operations performed by a single surgeon; ethnography was performed concurrently. Instruments without recorded use were eliminated, and 10 additional cases were performed utilizing the reduced tray. Logistic regression was used to estimate odds of instrument use across cases. Cohen's Kappa estimated agreement between RFID and ethnography. RESULTS: Over 15 cases, 37 unique instruments were used (median 23 instruments/case). A mean 0.64 (median = 0, range = 0-3) new instruments were added per case; odds of instrument use did not change between cases (OR = 1.02, 95%CI 1.00-1.05). Over 15 cases, all instruments marked as used by ethnography were recorded by RFID tracking; 7 RFID-tracked instruments were never recorded by ethnography. Tray size was reduced 40%. None of the 25 eliminated instruments were required in 10 subsequent cases. Cohen's Kappa comparing RFID data and ethnography over all cases was 0.82 (95%CI 0.79-0.86), indicating near perfect agreement between methodologies. CONCLUSIONS: Intraoperative RFID instrument tracking is a feasible, data-driven method for surgical tray reduction. Overall, RFID tracking represents a scalable, systematic, and efficient method of optimizing instrument supply across procedures.