Quantitative determination of all structural families of complex carbohydrate micronutrients was performed on bovine milk samples, milk-based infant formulas, and whey-based manufacturing raw materials. Differences found between formulas depended mainly on their whey: casein ratios. A solvent separation procedure was required for quantitative estimation of the gangliosides and neutral glycolipids within the fat fraction. All infant formulas except one contained slightly more gangliosides than bovine milk. Complex carbohydrates were consistently higher in the nonfat fraction. By gel permeation chromatography, an oligosaccharide subfraction was separated from a glycopeptide one. Oligosaccharide content of infant formulas increased as a function of the whey:casein ratio, and glycopeptides were found only in formulas made with whey components. Neuraminic acids from infant formulas were associated primarily with the glycoprotein fraction, except in hydrolysate-based preparations in which "precipitable" glycoproteins were converted into "soluble" glycopeptides by trypsin treatment. Because whey-based raw materials are very rich in all bovine milk glycoconjugates and oligosaccharides their increased use will result in high contents of these micronutrients in modern formulas.