Depilated skin of white pigs was exposed to different exposure time- irradiance combinations using CO2 laser radiation (10.6 microns). The lesions produced ranged from a mild erythema to partial tissue coagulation. The probability of producing a particular grade of lesion was then established for power densities within the range of 0.69-13.6 watts/sq. cm and exposure times of 0.2 to 40 sec. Data obtained are adequate to establish laser safety standards. A relatively simple model is discussed that describes the exposure parameters to produce threshold skin lesions.