ABSTRACT: There is good evidence that up until 8,500 years ago in the Middle East and 7,500 years ago in Europe, no human being on the planet consumed non-human milk or dairy products. So, on an evolutionary time-scale, non-human milk is a relative newcomer to the human diet, which is further reinforced by the fact that only about 35% of the world’s population expresses the phenotype of Adult Lactase Persistence. By using the evolutionary template, and knowing that milk is species specific, we would expect this new habit to have unintended consequences. But, as most foods, milk may have not only adverse effects, but also various beneficial effects. Indeed, some populations, such as traditional African pastoralists, have thrived on high milk diets for thousands of years. Nevertheless, the physiological purpose of milk is to be the sole food of infant mammals during the most accelerated growth period in postnatal development when endogenous production of hormones is low. As a result, in addition to possessing proteins, lipids, carbohydrates, vitamins and minerals, milk also contains various growth-stimulating steroid and peptide hormones and catalysts, transporters, and stabilizers that ensure their maximum bioactivity. Moreover, changes in dairy industry production methods resulted in steadily increasing milk hormone concentrations and bioavailability during the 20th century. The purpose of this lecture is therefore to discuss the endocrine effects of milk and dairy and some of its possible health consequences.