The present study was undertaken to establish an animal model of combined whole-body irradiation and thermal injury and to determine the effectiveness of early excision and closure of the burn wound in such a model. Whole-body irradiation over a range of doses resulted in a predictable mortality rate, with an LD50/30of 783 rad with 95% confidence limits of 737 and 823 rad. A controlled 10% body surface area full-thickness thermal injury resulted in no deaths in 30 animals. When combined with a standard nonlethal 10% thermal injury, varying doses of whole-body irradiation resulted in widely differing LD50/30values in three separate cohorts of rats. Excision and closure of a 10% burn 24 hours after exposure to 200 rads did not improve survival.