Lactoferrin is a multifunctional whey glycoprotein with a molecular mass of about 80 kDa. It is produced by various mammals and is found in milk, nasal secretions, saliva and tears, and it is in great abundance in human colostrum. It has intrigued scientists for decades. Lactoferricin and lactoferrampin are bioactive peptides derived from lactoferrin. Topics discussed in this book encompass: the primary structure and glycosylation pattern of milk lactoferrin, the inhibitory effect of lactoferrin on the hepatitis C virus, the anti-candidal activities of lactoferrin in systemic candidiasis, antimicrobial (antibacterial, antifungal and antiviral) and anticancer activities of lactoferricin, activities of lactoferrampin and the mechanisms involved, the properties and activities of lactoferrampin and lactoferricin-lactoferrampin chimera, dependence of the multiple effects of lactoferrinon receptors in different cell types, and clinical applications of lactoferrin.