BACKGROUND: Urea is a non-proteinaceous nitrogen source, often used as a substitute for raw ration protein in order to reduce the feeding cost of livestock. OBJECTIVES: The purpose of this study was to investigate the effects of substitution of different levels of slow-release urea with soybean  meal on feed intake, milk production and composition, and blood parameters of lactating cows in early lactation. METHODS: Twelve Holstein cows were selected at the third birthday, milk production of more than 30 kg per day, and from 10 to 100 days after birth, with four diets, the treatments included 0, 23, 0.46 and 0.69  % of slow-release urea was replaced by soybean meal. Feed intake was measured daily. The milk sample was taken on the day of the start of the experiment and was taken at intervals of 14 days. To measure glucose, urea, cholesterol, triglycerides, high density lipoprotein, and low blood levels, were determined  from the start of the test to the end of the test every two weeks. RESULTS: Consumption of feed, milk production and composition did not differ from experimental treatments. Glucose concentration and blood parameters (cholesterol, high and low density lipoprotein) did not differ between experimental treatments, but triglyceride and lipoprotein showed a very low density at zero (P <0.05). CONCLUSIONS: The results of this study showed that adding slow-release urea to the level of 0.69% had no negative effect on feed consumption, milk production and composition, and blood parameters.