Milk is a food with a complex chemical composition and, like other dairy products, it is rich in all the necessary nutrients important in human nutrition, which cannot be said for adulterated milk. Adulteration of milk is a growing problem today, and this term refers to any intentional reduction of milk quality by adding, replacing or removing certain ingredients. There are numerous additives that can be used to adulterate milk, such as starch, urea, preservatives and harmful chemicals (melamine, formalin, detergents), while dilution is the most common method. The removal of milk fat or mixing different types of milk is also considered to be adulteration. Some of the methods that can be used to prove adulteration, which are described in this paper, are: cryoscopy, NIR spectroscopy, MALDI-MS, RP-HPLC, chemical methods, immunological tests, ultrasound technique and electronic tongue. In addition to significantly reducing quality, adulterated milk can cause very serious health problems to consumers. For these reasons, it is necessary to carry out constant monitoring and regular inspections of milk producers in order to reduce the possibility of adulteration to a minimum.