In this study, glycoproteins and oligosaccharides with sialyl Lewis a, sialyl Lewis x, Lewis x, and Lewis y epitopes were isolated by ultracentrifugation and fast-protein liquid chromatography from human milk of mothers with term or preterm infants. The identification of these epitopes on whey proteins was achieved by monoclonal antibodies and lectins after Western blotting. Lactose-derived oligosaccharides were characterized by high-performance thin-layer chromatography and high-pH anion-exchange chromatography with pulsed amperometric detection. These carbohydrate epitopes which are potential ligands for selectins are not of cellular origin but appear in the soluble fraction of milk. Here, they are present as lactose-derived oligosaccharides (molecular weight < 10kD) or bound to proteins with a high molecular weight ( > 100 kD). Lewis antigens might represent another category of protective nonimmunological substances in human milk with the potential to influence inflammatory processes in human milk fed infants.