The functionalities of glycoprotein lactoferrin (LF) and glycomacropeptide (GMP) were discussed. LF is considered a multifunctional protein. Its absorption in the bowel; immune response; antioxidant, anti-carcinogenic and anti-inflammatory properties; and protection against microbial infection, were the most widely studied functions to date. Besides, promotion of balanced intestinal flora by preventing growth of harmful bacteria and stimulating bifidus, LF helps to secure a correct balance of the intestinal flora. Although, most of the proposed biological activities of LF are related to the binding of iron, the non-iron related functions have been described as well, such as regulation of iron metabolism, prevention of oxidation and control of cell or tissues damage (result of aging). Likewise, GMP, which is a carbohydrate-containing peptide formed from chymosin or pepsin digestion of κ-casein, exhibits several useful biological activities, including binding of cholera toxin and E. coli enterotoxins, inhibition of bacterial and viral adhesions, suppression of gastric secretions, promotion of bifidobacterial growth, and modulation of immune responses. GMP contains no aromatic amino acids and is therefore used for phenylketonuria (PKU) suffering patients. The carbohydratic parts bound to such glycoprotein or glycopeptide, may act as prebiotics in the intestine and colon.