Sugar chains are abundantly expressed on the outer surfaces of the vast majority of viral, bacterial, protozoan and fungal pathogens, as well as on the membranes of mammalian cells. This class of carbohydrate molecules is structurally diverse and characteristically suitable for storing biological signals for molecular and cellular recognition. Exploring the biological information contained in sugar chains is an important topic of current post-genomic research. To facilitate these investigations, we have focused on the development of carbohydrate-based microarray technologies. Two complementary platforms of carbohydrate microarrays, a method of non-covalent immobilization of carbohydrate antigens on micro-glass slides and a method of photo-coupling of saccharide moieties on a bioarray substrate, have been recently established by our laboratory and collaborators. In this presentation, we attempt to summarize our progress in using these technologies to explore the immunogenic sugar moieties, especially those that are expressed by viral pathogens (SARS-CoV and HIV-1) but share strong antigenic cross-reactivities with human cancers. Potential of this class of carbohydrate moieties in development of novel antiviral and anticancer strategies will be discussed.