The most economically relevant diseases in high yielding cows, especially during early lactation, are ketosis, hypocalcaemia and mastitis. Physiological variation of milk parameters can be identified precisely and economically by modern rapid analytical methods. The biochemical milk profile can be used as a mirror of the cow's metabolic status by investigating milk concentrations of chemicals including beta-hydroxybutyric acid, acetone, citrate, phosphate, potassium and sodium. Furthermore, changes in milk composition (e.g. somatic cells, lactose, minerals and enzymes) can be attributed to a disease-combating response of the cow in the case of mastitis, reduced secretory activity and alteration of blood-milk barrier. Factors predisposing to general or mammary gland diseases should be evaluated in combination with the major milk components (fat and protein) by measuring urea or allantoin in milk as indicators of a balanced diet. The potential for routine use of a combination of milk variables describing the general health and udder health status are discussed critically. Combined results of variation in milk composition may be useful for early identification of health problems. The earlier these health problems can be identified, the higher the chance for successful health management. In addition, aspects of practicability and economics are considered as well as such of the influence of the level of milk sampling (quarter, cow).