Glyco-coat changes on cancer cells due to aberrant glycosylation are potential targets for immune recognition through lectin-like receptors on immune cells. These cells include natural killer (NK), CD8+ and CD4+ lymphocytes, all reported to have, together with cytokines, important functions in antitumor immunity. The aim of this study was to evaluate a possible role of synthetic monodisperse multivalent neo-glycoconjugates, namely glycodendrimers, as a new approach to anticancer immune modulation through carbohydrate-mediated immune recognition. Octavalent polyamidoamine dendrimers functionalized with N-acetyl-glucosamine residues (PAMAM-GlcNAc8), with in vitro high affinity for the recombinant lymphocyte receptor NKR-P1A, were employed. To follow the fate of the compound, a fluorescent marker was conjugated to the tetra-branched semi-component of the dendrimer. Tumor development and immunity were evaluated in C57BL/6 mice. Animals were inoculated with B16F10 melanoma cells and underwent different protocols of PAMAM-GlcNAc8 administration. Advantages on survival and reduction of tumor growth were obtained in dose-dependent manner, by IP route. Increase of CD69+ cells in the spleen and their appearance inside the tumors, early progressive release of IL-1beta, a later production of INFgamma and IL-2 concomitant to an increment of CD4+ cells were observed. Cytotoxicity assays, performed ex vivo, showed an enhanced NK cell activity proportioned to the percentage of activated NK cells. Our data suggest that well-defined multivalent neo-glycoconjugates can stimulate an antitumor immune response engaging both innate and acquired immunity.