The ideal monitoring tool to evaluate free flap success should be noninvasive, continuous, and reliable. A new device, the ViOptix Tissue Oximeter (ODISsey) based on near-infrared spectroscopy was evaluated in 30 patients undergoing autologous tissue perforator free flap breast reconstruction with continuous monitoring of the flap during elevation, transfer, and the postoperative period. The device accurately reflected the ischemic drop in oxygen saturation during flap transfer, and the hyperemic response after flow was reestablished. There were no flap failures, but in two patients, the device indicated a venous thrombosis before it was clinically obvious and allowed for expeditious flap salvage. The noninvasive nature of the device, the ability to replace and move the probe in the postoperative period, and the measurement of end organ oxygenation are all advantages over other currently available techniques.