Aberrantly glycosylated tumor antigens represent promising targets for the development of anti-cancer vaccines, yet how glycans influence immune responses is poorly understood. Recent studies have demonstrated that GalNAc-glycosylation enhances antigen uptake by dendritic cells as well as CD4(+) T-cell and humoral responses, but prevents CD8(+) T-cell activation. Here, we briefly discuss the relevance of glycans as candidate targets for anti-cancer vaccines.