A system was developed to determine the potential role of infrared imaging as a tool for localizing anatomic structures and assessing tissue viability during laparoscopic surgical procedures. A camera system sensitive to emitted energy in the midinfrared range (3-5 micron) was incorporated into a two-channel visible laparoscope. Laparoscopic cholecystectomy, dissection of the ureter, and assessment of bowel perfusion were performed in a porcine model with the aid of this infrared imaging system. Inexperienced laparoscopists were asked to localize and differentiate structures before dissection using the visible system and then using the infrared system. Assessment of bowel perfusion was also conducted using each system. Infrared imaging proved to be useful in differentiating between blood vessels and other anatomic structures. Differentiation of the cystic duct and arteries and transperitoneal localization of the ureter were successful in all instances using the infrared system when use of the visible system had failed. This system also permitted assessment of bowel perfusion during laparoscopic occlusion of mesenteric vessels. These initial studies demonstrate that infrared imaging may improve the differentiation and localization of anatomic structures and allow assessment of physiologic parameters such as perfusion not previously attainable with visible laparoscopic techniques. It may thus potentially be a powerful adjunct to laparoscopic surgery.