Both intracardiac repair and fine anastomotic procedures are hard to visualize in the sterile operative field. To overcome this problem, we have recently developed an endoscope video system for intraoperative monitoring in open heart surgery. The endoscope can be introduced into the cardiac cavity in a sterile fashion and thus be used to visualize intracardiac lesions as well as the operative procedures. This endoscopic video monitoring system is considered to be useful not only for thoracic surgery but also for cardiac surgery as well.