Study Objective: To determine how well Laser-Guard protects polyvinyl chloride (PVC) endotracheal tubes from the carbon dioxide (CO 2) laser. Design: Bare and Laser-Guard-protected PVC endotracheal tubes were tested with 5 L/min of oxygen (Oz) passing through them. Setting: Research laboratory of a university-affiliated metropolitan medical center. Interventions: After moistening the Laser-Guard-protected endotracheal tubes, we subjected the tubes to CO 2 laser radiation at 10 and 70 watts until combustion occurred or 60 seconds had elapsed. Measurements and Main Results: The bare PVC tube ignited and a “blowtorch” fire occurred after 3 seconds of CO 2 laser use at 70 watts. The moistened Laser-Guard-protected PVC endotracheal tubes were not significantly damaged by 1 minute of laser use at 70 watts. Conclusions: Laser-Guard protects the shafts of combustible PVC endotracheal tubes from direct, high-power, continuous CO 2 laser radiation.