In the paper urea content in milk of cows fed mainly on feeds from permanent grassland was analysed. The relationship between urea level in milk and other productivity traits was also estimated. Urea content in milk was 250 mg/l, which means it was optimal. The season of feeding influenced the level of this parameter the most. In summer urea content was 123 mg/l higher and it indicated protein excess in the feeding stuff. In the summer season a higher milk yield and a lower protein, fat and dry matter content were also found. Coefficients of correlations show that an increase the urea level can decrease the daily milk yield and protein, fat and dry matter content. It was found that the properly balanced feed ration in relation to energy and protein will permit to obtain milk production consistent with the cows’ genetic potential as well as the optimum milk composition.