The presence of hormones in consumable food items has been known for many years, but recent popular press articles about the presence of these hormones in food have led to increased public interest. While there is evidence of ingested protein hormone factors affecting the gastrointestinal tract (GIT), there is no evidence of absorption of the protein hormones after gut closure. Lipid-soluble hormones are absorbed but are converted enzymatically to less bioactive components in the intestinal and hepatic tissues. A number of hypotheses have been put forward to explain the rationale behind these secreted bioactive components appearing in milk: (1) they are a means of mammary disposal; (2) the hormones are autocrine/paracrine factors that have important roles in the regulation of mammary cells; (3) these factors affect the function of the GIT of the newborn; (4) these factors are absorbed by the GIT and have peripheral functions in the newborn; and (5) they do not have any function, they just result from normal biological processes involved in the secretion of milk. This article explains the mechanism of appearance of milk hormonal factors, lists major hormonal factors that are present in milk, and considers the evidence for some of the proposed concepts that provide a rationale for their appearance.