High blood-flow rate and considerable metabolic activity render the myocardium a possible candidate for infrared (IR) imaging. Cardiothermography is the term used for recording the heart surface temperature. It is a useful tool in monitoring coronary perfusion through epicardial heat emission changes. Elevated heat-emission indicates increased coronary blood flow, while decreased emission represents hypoperfusion. The aim of our study is the early intraoperative cardiothermographic evaluation of arterial and venous bypass graft patency and the quantitative assessment of the temperature changes of the revascularized area. Infrared imaging was complemented by electromagnetic flow measurements on the venous grafts.