Protective capabilities were studied of carboxymethylated (1-->3)-beta-D-glucan from Saccharomyces cerevisiae cell wall against lipid peroxidation in phosphatidylcholine liposomes induced by OH radicals produced with Fenton's reagent (H2O2/Fe2+) and also by microwave radiation using absorption UV-VIS spectrophotometry. A significant decrease in the conjugated diene production, quantified as Klein oxidation index, was observed in the presence of a moderate amount of added glucan. Increase of the oxidation index was accompanied with enhanced carboxyfluorescein leakage as a result of liposome membrane destabilization. This process was markedly suppressed with glucan present in the liposome suspension. Therefore, glucan may be considered as a potent protector against microwave radiation-induced cell damage.