beta-Glucans belong to the class of substances known as biological response modifiers with a broad range of activity. We have investigated two types of glucans: (1-->3)-beta-D glucan from the baker's yeast Saccharomyces cerevisiae and beta-glucan-chitin complex from the mycelium of filamentous fungus Aspergillus niger. Since these fibrillar beta-glucans are insoluble in water, their water-soluble derivatives--carboxymethyl glucan (CM-G), sulfoethyl glucan (SE-G), and carboxymethyl chitin-glucan (CM-CG) were prepared and tested. The aim of the present work was to investigate the protective effect of the prepared glucan derivatives against oxidative DNA damage induced by H2O2 and visible light-excited Methylene Blue in V79 hamster lung cells. The level of DNA damage (DNA strand breaks) was measured using the single cell gel electrophoresis, so called comet assay. Our findings demonstrate that all three tested glucans reduce oxidative DNA damage. The ability to reduce genotoxic activity increased in the order: CM-G<SE-G<CM-CG. We suggest that the analyzed glucans exhibit protective effects against oxidative damage to DNA as a consequence of scavenging of both *OH radicals and singlet oxygen.