Description: Four green iguanas scheduled for euthanasia were used to compare the extent of collateral tissue damage associated with CO2 laser and 4ч0 MHz radiosurgery. The iguanas were anaesthetised and a series of three skin and three muscle incisions was made by 4ч0 MHz radiosurgery (0ч18 mm wire electrode, 25 W, cut mode) and CO2 laser (0ч3 mm ceramic tip, 15 W focused beam super-pulse mode), and three incisions were made with a scalpel blade as controls. Following euthanasia, a total of 60 skin and 36 muscle sections were evaluated histologically. Radiosurgery and the laser both produced bloodless incisions, but radiosurgery caused significantly less collateral tissue damage in the skin (307 [97] v 386 [108] хm) and the muscle (18 [7] v 91 [15] хm)