Carbohydate-carbohydrate recognition is emerging today as an important type of interaction in cell adhesion. One Ca2+mediated homotypic interaction between two Lewis X determinants (Le X ) has been proposed to drive cell adhesion in murine embryogenesis. Here, the adhesion energies of lipid vesicles functionalised with glycolipids bearing monomeric or dimeric Le X determinants were measured in NaCl or CaCl2 media with the micropipette aspiration technique. These experiments on Le X with an environment akin to that provided by biological membrane confirmed the existence of this specific calcium dependant interaction of monomeric Le X . In contrast, dimeric Le X produced a repulsive contribution. By using a simple model involving the various contributions to the adhesion free energy, specific and non specific interactions could be separated and quantified. The involvement of calcium ions has been discussed in the monomeric and dimeric Le X lipids.