Suture ligation of blood vessels during surgery can be time-consuming and skill-intensive. Energy-based, electrosurgical and ultrasonic devices have recently replaced sutures for many surgical procedures, providing rapid hemostasis during surgery. However, these devices have the potential to create large collateral zones of thermal damage and tissue necrosis. This study explores infrared (IR) lasers as an alternative technology for rapid and precise thermal coagulation and sealing of blood vessels. Eight near-IR lasers (808, 980, 1075, 1470, 1550, 1850- 1880, 1908, and 2120 nm) were tested. Preliminary studies were performed using fresh porcine renal vessels, ex vivo, with diameters of 1-6 mm, compressed to a thickness of 0.4 mm. A linear beam profile was then applied normal to the vessel for narrow, full-width thermal coagulation. Laser irradiation time was 5 s. Vessel burst pressure measurements were used to determine seal strength. The 1470 nm laser wavelength sealed a wide range of vessel diameters from 1-6 mm. Other lasers (1550, 1850-1880, and 1908 nm) also sealed vessels, but were limited by suboptimal seal pressures, excessive charring, and/or limited power output preventing treatment of large vessels.