It is demonstrated that energostim, an aqueous mixture of NAD § cytochrome c, and inosine possesses pronounced antihypoxic activity. Energostim increases by 26-fold the survival rate of rats with low resistance to hypoxia under conditions of hypobaric hypoxia. Administration of energostim before the "rise" in a pressure chamber prevents a decrease in the brain content of ATP in rats with high resistance to hypoxia under the conditions of maximum hypoxia and increases it in rats with low resistance to hypoxia. Energostim has no effect on the survival rate of high-resistant rats in acute hypobaric hypoxia and on the brain content of macroergic substances in low-and high-resistant rats when agony is not developed on "the critical height" and there is no deficiency of macroergic substances.