Mathematical analysis was used to compare the antihypoxic action of alpha-tocopherol, inosine and oxidized NAD under long-term extracorporeal circulation. Of the drugs studied, oxidized NAD form was demonstrated to be the most active, inosine appeared less active, and alpha-tocopherol still less active. It is advisable to study more thoroughly the effect of oxidized NAD under long-term extracorporeal circulation.