There are seven essential macroelements (sometimes referred to as macrominerals): sodium, potassium, chloride, calcium, phosphorus, and magnesium, all of which occur in milk. The mineral content of milk is not constant but is influenced by a number of factors such as stage of lactation, nutritional status of the animal, and environmental and genetic factors. Furthermore, the concentration of many minerals shows a wide variation due to these and other factors such as analytical errors and contamination during milk collection and from processing equipment and processes. This article overviews the content and chemical form (which may influence bioavailability) of macrominerals in milk and dairy products as well as the nutritional roles, recommended intakes, and hazards of deficiency or excess of these seven elements. It also overviews the nutritional significance of these macrominerals by comparing the amounts provided by 1 l of milk with recommended daily intakes for these elements, as well as by computing (using data on dietary surveys) the actual contribution made by diary products to the total intake of macrominerals. The contribution of cow's milk and milk products to the diet in Western countries is significant for sodium, potassium, chloride, calcium, and phosphorus. While sodium, potassium, and chloride are believed to be almost totally absorbed from milk and infant formulae, the bioavailability of calcium is much less (between 21 and 45%). There is little information on the bioavailability of magnesium in milk and infant formulae. There is a paucity of data regarding the bioavailability of macrominerals from other dairy products.