Use of the tacticts of multistage surgical treatment on the model of combined radiation-and-mechanic injury. The article provides information on the use of the tactics of multistage surgical treatment (MST), which allows increasing survival value in patients with polytrauma. There are no descriptions of possibility of the use of this tactics in case of combined radiation-and-mechanic injuries in available literature. During an experimental research underwent on 25 sheep it was found that in case of MST implementation there is a significant decrease of intraoperative and postoperative lethal outcome in comparison with traditional tactics. In animals, underwent MST, were defined more laudable course of radiation syndrome. Analysis of laboratory peripheral blood indexes allowed making conclusion, that conducting final surgical intervention (3'd stage of MST) during the first 24 hours after abbreviated surgical intervention allows finishing surgical treatment and intensive care before the beginning of acute radiation syndrome and doesn't counter classic recommendations concerning the treatment of combined radiation-and-mechanic injuries.