The IZdraK program (Cow Health Index) performs a calculation of the selection health index of cows of Holstein breed. It is based on the requirement to increase resistance of Holstein cows for clinical mastitis and foot and claw disorders. The index includes health traits: claw disorders, infectious claw diseases and non-infectious claw lesions and clinical mastitis; as well as the production traits, the number of somatic cells in the milk and the type traits. The calculation is based on breeding values of cows for the traits of the selection index and on the economic weights of the traits calculated using the complex bio-economic model of the ECOWEIGHT program (Wolf et al., 2013). In the program, the so-called sub-index of cow health is also calculated as a supplementary index. It includes only health traits. The cow health index and the cow health sub-index are calculated only if the breeding values for the animal are known for all the traits included in the index. In another case, the cow health index is zero.