A novel disialoganglioside has been isolated from rat ascites hepatoma AH 7974F cells. Based on the results of sequential enzymatic hydrolysis and gas chromatography-mass spectrometry analysis of the methylated sugars, the structure was concluded to be (Formula: see text) Proton magnetic resonance spectra of the ganglioside have been obtained and peaks of protons were assigned based on the analytical results. This is the first report on the occurrence in mammalian cells of an example of this new series of gangliosides which has NeuAc linked to the C6 position of GalNAc of the gangliotetraosyl backbone. The present ganglioside was named GD1 alpha.