Decoctions of herbal mixtures I (including 30% Filipendula ulmaria meadowsweet grass, 10% bilberry shoots, and 60% Bergenia crassifolia green leaves) and II (60% meadowsweet grass, 10% bilberry shoots, and 30% bergenia green leaves) exhibited antioxidant activity. Biologically active substances of herbal mixture I exhibited predominantly catalytic decomposition of hydrogen peroxide formed during electroreduction of oxygen. Active substances of herbal mixture II interacted with oxygen radicals generated as a result of oxygen electroreduction on the electrode surface (EC mechanism) and were more effective than both dihydroquercetin and ascorbic acid. Herbal mixtures I and II normalized the content of thiobarbiturate-reactive products in brain homogenates under conditions of hypoxia-activated lipid peroxidation. In addition, herbal mixture II reduced the concentration of antiradical antioxidants in the lipid extracts. The antioxidant properties were inherent to a greater extent in mixture II dominated by meadowsweet grass, which contained the most complete sum of biologically active phenolic substances (simple phenols, flavonoids, hydroxycoumarins, phenolcarboxylic acids, mainly hydrolyzable tannins), amino acids, and macro- and microelements.