Sialic acid-containing glycosphingolipids, known as gangliosides, have important roles in several cellular events. Gangliosides are essential components of the so-called lipid rafts, which are membrane microdomains where these glycolipids associate with proteins that participate in cell signaling cascades. The GM3(Neu5Gc) ganglioside in particular has been detected in breast cancer, melanoma, non-small cell lung cancer, Wilms tumors, neuroectodermal tumors, sarcomas and thyroid carcinomas and malignancies from the digestive and genitourinary systems. Three different immunotherapeutic approaches have focused on this molecule as their target: a molecular vaccine, an antiidiotypic antibody-based vaccine and the use of monoclonal antibodies (mAbs) able to discriminate between GM3(Neu5Gc) and GM3(Neu5Ac).