Percutaneous endoscopic techniques for biliary surgery would be facilitated by methods of welding biliary tissue. To further investigate laser methods for fusing biliary tissue, we compared the time 0 bursting strength of two variations of near-infrared laser closure against polyglycolic acid suture controls. These time 0 studies were performed with a gallium-aluminum-arsenide semiconductor diode laser with a major wavelength output of 808 ± 1 nm and an energy density of 4.8 J/cm2. Using the 808 nm laser and indocyanine green dye to enhance laser energy uptake, closure of gallbladder incisions was accomplished with and without addition of fibrinogen to the target site prior to laser exposure. Without fibrinogen, the laser welds burst at 77 mm Hg, while fibrinogen soldering yielded a bursting pressure of 194 mm Hg. Sutured welds leaked at 215 mm Hg. Survival studies were performed with a mid-infrared 2.15 micron thulium-holmium-chromium:YAG laser producing 200 microsecond 300 millijoule pulses at 3 Hz (peak power .75 megawatts/sq cm, fluence 150 joules per square centimeter). The healing of mid-infrared and polyglycolic suture closures of gallbladder incisions were compared at 1,2,3, and 4 weeks. All closures healed without evidence of leakage or infection. Laser welded cholecystostomy sites were completely ingrown with fibrous tissue by 2 weeks post-operatively and re-epithelialized by 3 weeks after operation. Suture closed wounds were still without complete epithelization 4 weeks after the procedure. Laser welding, particularly with fibrinogen reinforcement, may be a useful technique in future developments in percutaneous endoscopic biliary surgery.