Abstract: Breastfeeding is superior to formula feeding because it has specific and non-specific factors that have long term consequences for early metabolism and disease later in life. Human milk enhances the immature immunologic system of the neonate and strengthens host defense mechanisms against infective and other foreign agents. Mechanisms that explain active stimulation of the infant`s immune system by breastfeeding are through bioactive factors in human milk such as hormones, growth factors, colony stimulating factors and specific nutrients. Human milk may show a reduced occurrence of disease because: 1) Mammalian evolution promotes survival advantage. 2) Factors that promote gastrointestinal mucosal maturation. 3) Factors that decrease the incidence of infection and alter the gut microflora. 4) Functional immunomodulatory and anti-inflammatory factors. 5) Hormones, growth factors and cytokines that may modulate the development of disease. 6) Reduced exposure to foreign dietary antigen. Following the termination of breastfeeding there is evidence of ongoing protection against illness due to influences on the immune system mediated via human milk. Industry continues to attempt to improve formula with the addition of compounds such as fatty acids, oligosaccharides, nucleotides and lactoferrin. However, human milk has such far reaching effects on the infant`s immune response that normal development depends heavily on its provision. All mothers should be encouraged and supported to continue breastfeeding for six months and beyond in order to promote the good health of their infants.