Although the concentrations of carbohydrate in the colostrum and in the mid-lactation milk of polar bear (Ursus maritimus) were similar, the oligosaccharide patterns differed. The colostrum sample contained Neu5Ac(alpha2-3)Gal(beta1-4)Glc (3'-N-acetylneuraminyllactose), GalNAc(alpha1-3)[Fuc(alpha1-2)]Gal(beta1-4)Glc (A-tetrasaccharide), Fuc(alpha1-2)Gal(beta1-4)Glc (2'-fucosyllactose) and Gal(beta1-4)Glc (lactose). The mid-lactation milk contained Gal(alpha1-3)[Fuc(alpha1-2)]Gal(beta1-4)[Fuc(alpha1-3)]Glc (B-pentasaccharide), GalNAc(alpha1-3)[Fuc(alpha1-2)]Gal(beta1-4)[Fuc(alpha1-3)]Glc (A-pentasaccharide), Gal(alpha1-3)[Fuc(alpha1-2)]Gal(beta1-4)Glc (B-tetrasaccharide), A-tetrasaccharide, Gal(alpha1-3)Gal(beta1-4)[Fuc(alpha1-3)]Glc (3-fucosylisoglobotriose), Gal(alpha1-3)Gal(beta1-4)Glc (isoglobotriose) and lactose. The dominant saccharides in the colostrum were 3'-N-Acetylneuraminyllactose and lactose, whereas isoglobotriose was the dominant saccharide in the mid-lactation milk in which lactose was only a minor component. Isoglobotriose, which had previously been found to be a dominant saccharide in mature milk from the Ezo brown bear, the Japanese black bear and the polar bear, was not found in the polar bear colostrum.