Trisialogangliosides were isolated from bovine adrenal medulla by DEAE-Sephadex A-25 and Iatrobeads column chromatography. Their structures were elucidated by sugar analysis, neuraminidase digestion, and permethylation studies. The complete structures of trisialogangliosides, A to D, were identified as follows. A: GT1b, IV3NeuAc, II3 (NeuAc)2-GgOse4Cer. B: GT1b(NeuAc/NeuAc-NeuGc-); IV3NeuAc, II3 (NeuAc alpha 2-8 NeuGc-)GgOse4Cer. C: GT1b (NeuGc/NeuAc-NeuAc-); IV3NeuGc, II3 (NeuAc alpha 2-8 NeuAc-)GgOse4Cer. D: GT1b (NeuAc/NeuGc-NeuGc-); IV3NeuAc, II3 (NeuGc alpha 2-8 NeuGc-)GgOse4Cer. Gangliosides B, C, and D, which contain N-glycolylneuraminic acid, have not previously been reported in the literature.