In this focused issue, we focused on structural analysis of glucans as the tool for better understanding of the relationship between the physicochemical characteristics and biological activities. Hand-by-hand with the possible heterogeneity of natural molecule goes the search for optimalization of glucan-based oligosaccharides. The next part of this issue is devoted to possible use of glucan in human medicine. Article on glucan effects on bone marrow describes not only animal data, but also hypothesize about the use of glucan in support of chemotherapy and irradiation. These experiments are further developed in an article on glucan-based protection of DNA against radiation damage.