The effect of free radicals scavengers (SOD and allopurinol) on the adherence of leukocytes and the blood flow of capillaries in spinotropizus muscle was observed in rats with burn shock. The changes in water content in heart, liver, lung, spleen, kidney and burned skin were measured. The survival time of the animals was recorded. The results showed that the number of the adherence of WBC decreased obviously, the amount of open capillaries increased, and the survival time of the animals with thermal injury prolonged by pretreating with SOD and allopurinol. The results of SOD were better than that of allopurinol. SOD also prevented the increase of water content in the lung and the burned skin, while allopurinol did not have this effect. It was shown that the therapeutic effect of SOD would appear if the medicine were given before or immediately after burn. However when SOD was administered half an hour after burn, there was no effect on adherence of WBC. These results confirm that superoxide free radical may be responsible for the adherence of WBC and hypoperfusion of microcirculation during burn shock. The scavengers have an important role in preventing microcirculatory disturbances, but it should be used as early as possible after thermal injury in order to block the response chain caused by free radicals.