Sudden Infant Death Syndrome (SIDS), the leading cause of infant death from one to six months in the developed world, strikes approximately two infants per 1000 live births in the U.S. The characteristics of the infants who die suddenly and unexpectedly are non-specific; none are universal except for the age distribution. Therefore, an infant is recognized to have died from SIDS only after thorough examination fails to demonstrate any other cause for the death. It is the purpose of this paper to review the most populat hypotheses of the causes of SIDS and try to explain through published scientific findings how breastfed infants appear to be protected from this condition. Many hypotheses have been proposed to explain SIDS. Some deficiencies/problems are related to the infant, such as a defect in sleep and/or breathing control, severe infant botulism, infections, reactions to immunizations, hypersensitivity to cow's milk, "maternal deprivation syndrome." Other causes are attributed to maternal circumstances, such as lower socioeconomic status, prenatal health, smoking, and the winter season. Additional suggestions of potential causes of SIDS include baby's thiamine deficiency, and hormonal and/or biochemical imbalance. The occurrence of most of these circumstances can be associated with a lack of breastfeeding. Because SIDS occurs much less frequently in breastfed infants, it is speculated that breastfeeding protects infants against SIDS. However, scientific literature lacks uniformity in the definitions of breastfeeding (whether partial and exclusive). This specification is necessary to select control infants to elucidate the well documented substantial lower rate of incidence of SIDS in breastfed babies.