The purpose of this project was to develop an animal model for a fluoroscopically guided application of the contact neodymium-yttrium aluminum garnet (Nd-YAG) laser in the bile duct and identify the factors affecting the extent of damage to the duct wall. This model permits cholangiographic visualization of the duct during laser application. Laser damage is limited by using contact probes and firing the laser while slowly pulling the probe proximally into the duct. Sixteen common bile duct laser burns were produced in 14 dogs. Power settings of 8-25 W were used. The tension of the contact probe along the duct wall, termed "wall tension," was varied through intraoperative manipulation in order to mimic a variety of ductal geometries that might be encountered in clinical use. The authors produced duct damage ranging from a superficial burn to perforation. Power and wall tension were the most important factors in determining the depth and circumference of damage, and the use of 15 W or less did not perforate the duct.