The main component of the ganglioside(1) mixture from the brain of the adult amphibian Xenopus laevis accounts for 35% of the total, as lipid bound sialic acid. This ganglioside has been purified and characterized by thin layer chromatography, partial and exhaustive enzymatic hydrolysis with sialidase, TLC-overlay procedures with anti-Gg(4)Cer and anti-Neu5Acalpha6GalNAcbeta specific monoclonal antibodies and mass spectrometry. All together the results suggest the following structure: Neu5Acalpha8Neu5Acalpha3Galbeta3(Neu5Acalpha8Neu5Acalpha6)GalNAcbeta4Galbeta4Glcbeta1Cer, or, IV(3)-alpha-Neu5Ac(2),III(6)-alpha-Neu5Ac(2)-Gg(4)Cer.