It was shown using various methods that the radical scavenging and radical scavenging activities of chitosan conjugates with phenolic antioxidants of plant origin significantly exceed the corresponding values of their low molecular weight analogs (gallic and syringic acids, quercetin and dihydroquercetin). Cytogenetic analysis of human peripheral blood lymphocytes demonstrated that the conjugates showed pronounced antimutagenic efficiency when the cells were γ-irradiated in vitro at a dose of 2 Gy.