High-pressure (HP) treatment of food products is a novel processing technique during which the product is treated in a vessel of suitable strength at a high pressure, generally in the range 100–1000 MPa. As a result, several constituents and properties of the treated product are altered. HP-induced changes in the constituents and properties of milk are arguably among the most extensive of the range of food products studied to date. HP treatment of milk induces solubilization of minerals associated with the casein micelles, denatures whey proteins and, depending on pressure, can either induce aggregation or disruption of the casein micelles. These HP-induced changes in milk constituents affect the properties of the milk; cheesemaking properties of milk can be enhanced considerably, indicating potential application of HP treatment in this area; furthermore, encouraging results have also been reported for HP treatment of milk prior to yogurt manufacture. HP treatment of milk also affects its microflora; however, considerable variation in baroresistance between bacterial species and strains exists. Further applied research appears warranted to establish the full commercial potential of HP treatment of milk.