A feeding trial was conducted to examine the effects of feeding polyurethane coated urea on lactating performance and plasma biochemical indices of dairy cows. Twenty-four Holstein lactating cows were allotted to one of three treatments in a completely randomized design. The three treatments with isonitrogenous diets (17.0% CP) were: 1) diet with soybean meal （SBM group）; 2) diet with polyurethane coated urea （PCU group）; 3) diet with feed grade urea （FGU group）. The results showed as follows: compared with FGU group, dry matter intake of cows in PCU group and SBM group were significantly increased (12.8%, 12.6%, P=0.02); milk yield was increased from 32.48 kg/d to 34.48 and 34.53 kg/d, but no significant difference was found (P>0.05); milk protein yield tended to increase (P=0.06). Cows in FGU group had lower milk protein ratio (P=0.04) and higher milk urea nitrogen concentration (P=0.03) than those in the other two groups. Compared with FGU group, plasma urea nitrogen concentration in PCU group (16.7 mg/dL) and SBM group (16.4 mg/dL) were significantly decreased (P=0.05). Milk urea nitrogen had a positive correlation with plasma urea nitrogen (R2=0.85). It is concluded that polyurethane coated urea can partially substitute soybean meal in the diet of dairy cows without impairing their lactating performance.［Chinese Journal of Animal Nutrition, 2010，22（6）:1672-1678］