The aim of the study was to determine the protective action of extracts from apple, strawberry and chokeberry with respect to linoleic acid and the biological membrane exposed to oxidation induced by physicochemical factors. The activity of the extracts was determined by measuring inhibition of lipid oxidation in red blood cell membrane, induced with UVC radiation and the AAPH radical. The protective effect of the extracts was essayed fluorimetrically and spectrophotometrically. These results together with the ones obtained earlier explain the mechanism of the interaction between the extracts and the red blood cell membrane. The mechanism consists in the incorporation into the membrane and screening the cell against oxidation. The results indicate that the extracts possess very good antioxidant properties, since at the highest concentrations used (0.1 mg/mL) they protect the biological membranes almost entirely against oxidation. Among the extracts studied the best antioxidant properties were exhibited by the apple fruit, which gave 80% or 100% protection of the membrane at 0.05 mg/mL concentration of dry matter, for UVC and AAPH inductors, respectively.