Advances in miniaturization and microelectronics, coupled with enhanced computing technologies, have combined to see modern infrared imaging systems develop rapidly over the past decade. As a result, the instrumentation has considerably improved, not only in terms of its inherent resolution (spatial and temporal) and detector sensitivity (values ca. 25 mK are typical) but also in terms of its portability: the considerable reduction in bulk has resulted in light, camcorder (or smaller)-sized devices. Importantly, cost has also been reduced so that entry to the eld is no longer prohibitive. is attractive combination of factors has led to an ever-increasing range of applicability across the medical spectrum. Whereas the mainstay application for medical thermography over the past 40 years has been with rheumatological and associated conditions, usually for the detection and diagnosis of peripheral vascular diseases such as Raynaud’s phenomenon, the latest generations of thermal imaging systems have seen active service within new surgical realms such as orthopedics, coronary by-pass operations, and also in urology. e focus of this chapter relates not to a specic area of surgery per se, but rather to a generic and pervasive aspect of all modern surgical approaches: the use of energized instrumentation during surgery. In particular, we will concern ourselves with the use of thermal imaging to accurately monitor temperature within the tissue locale surrounding an energy-activated instrument. e rationale behind this is that it facilitates optimization of operation-specic protocols that may either relate to thermally based therapies or else to reduce the extent of collateral damage that may be introduced when inappropriate power levels, or excessive pulse durations, are implemented during surgical procedures.