Here we showed for the first time that (i) the sialic acid linkage position in L1CAM could effectively discriminate between the VGP primary and the metastatic stage of human melanoma, and (ii) A1[3]G(4)2S2-3 oligosaccharide is a new melanoma-associated carbohydrate antigen, absent from the normal cell surface and resulting from alteration of N-glycan biosynthesis. Here, L1CAM is linked to melanoma.