In the article, the mineral nutrition in dairy cows is discussed. Above all, it is focused on calcium (Ca) and phosphorus (P), their physiological functions and homeostasis. The concentrations of Ca and P in forage and feed on some farms are listed, and the levels of filling the requirements for Ca and P in dairy cows throughout the calving to calving interval are assessed. The results indicate a great variability of Ca and P levels in forage and their insufficient supply during the calving to calving interval of dairy cows.