Three complete diets with crude protein 16% and energy value 9,4 MJ ME/kg DM were formulated using different combinations of high and low-degradable protein sources. Diet A was formulated with only natural protein sources (55% UDP), diet A1 contained 1,6% urea in the total diet (41% UDP) and diet A2 contained 1,0% urea in the total diet (47% UDP). The experimental diets were allocated to 21 cows per treatment from week 4 through 33 of lactation. From week 4 through 17 of lactation the average milk production was 28,5; 27,8 and 28,1 kg/d for diets A, A1 and A2 respectively. During the total experimental period from week 4 through 33 the average milk production was 23,8; 23,8 and 22,6 kg/d for diets A, A1 and A2 respectively. A level of up to 1,6% urea (total diet) would cause no fall in milk production of high-producing dairy cows when included into 16% crude protein complete diets with an abundance (when compared to the 1980 ARC specifications) of UDP supplied. There was a tendency for ttle difference in milk production between treatments to increase as the production potential of the cows increased. Therefore only up to 1% urea in the total diet, supplemented with high-quality, low·degradable protein sources providing 47% UDP is advocated for exceptionally high producers when compared to diets providing 41 and 55% UDP. This study has shown that urea can be utilized effectively and economically by high-producing cattle during early lactation when the crude protein level is 16% and UDP are in excess.