Lactoferrin （LF）, also known as lactotransferrin （LTF）, is a multifunctional protein of the transferrin family. Lactoferrin is a globular glycoprotein with a molecular mass of about 80 kDa that is widely represented in various secretory fluids. Lactoferrin is also present in secondary granules of PMNs and is secreted by some acinar cells. Lactoferrin belongs to the innate immune system. Apart from its main biological function, namely binding and transport of iron ions, lactoferrin also has antibacterial, antiviral, antiparasitic, catalytic, anti-cancer, and anti-allergic functions and properties. Lactoferrin interacts with DNA and RNA, polysaccharides and heparin, and shows some of its biological functions in complexes with these ligands. Lactoferrin supplements reduce the risk of respiratory tract infections, based on a recent meta-analysis of randomized controlled trials. Lactoferrin levels in tear fluid have been shown to decrease in dry eye diseases such as Sj?gren's syndrome.