Vapor produced by the carbon dioxide laser during the vaporization of papillomavirus-infected verrucae was analyzed for viral DNA content. Two models were used for evaluation: an in vitro cutaneous bovine fibropapilloma and an in vivo human verruca model. Four bovine fibropapillomas were exposed to various laser parameters with power densities of 38,200 to 130 W/cm2 and energy fluences of 3820 to 130 J/cm2. The generated vapor was collected in a chamber in line with a vacuum system. Hybridization with bovine papillomavirus DNA probes revealed intact bovine papillomavirus DNA for all power densities and energy fluences used. The laser vapor from seven patients undergoing carbon dioxide laser therapy for plantar or mosaic verrucae was also collected. Laser parameter settings were similar to those usually chosen for clinical tissue vaporization. Intact human papillomavirus DNA was present in the vapor from two of seven patients. These studies indicate that intact viral DNA is liberated into the air with the vapor of laser-treated verrucae. It would be prudent for all practitioners who use the laser in treating patients with viral infections or conditions associated with viruses to practice extreme care and safety throughout the laser procedure.