Objective To evaluate the role of equivalent uniform dose (EUD) in planning optimization of intensity-modulated radiotherapy (IMRT) for prostate cancer.Methods Ten patients with prostate cancer were randomly selected who treated with IMRT.For these patients,the treatment plans were designed with dose-volume objectives.Based on these plans,new plans were designed through replacing the dose-volume objectives with maximum EUD for rectum,bladder and small bowel,while keeping the dosevolume objectives unchanged.Comparison was made between the new plans and the former cones by paired t-test.Results The conformity index of planning target volume was better with EUD optimization compared to dose-volume (1.00 ± 0.04 ∶ 0.94 ± 0.04,t =3.80,P =0.04).The D53,D30 and Dicm3 for rectum was better with EUD optimization compared to dose-volume (24.4 ± 2.7 ∶ 25.5 ± 2.6,t =-3.82,P =0.004,34.1 ±4.3∶39.1±2.1,t=-3.80,P=0.004 and51.4±1.0∶51.8±0.9,t=-2.42,P=0.039),with V10,V20 for bladder and V10,V20,V30,V40 for small bowel also better with EUD optimization (92.2 ±6.2∶99.4±1.1,t=-4.28,P=0.002;70.7±5.7∶78.7±6.3,t=-3.10,P=0.013 and 62.2±30.2∶74.7 ±30.0,t =-4.18,P =0.002;34.3 ±26.3∶46.5 ±30.9,t =-5.46,P =0.000;17.1 ±17.0∶25.1 ±22.6,t=-3.52,P=0.007;10.6± 11.5∶ 15.6± 16.1,t=-2.64,P=0.030).Conclusions The conformity index of planning target volume is better with EUD optimization compared to dose-volume.And the dose to rectum,bladder and small bowel can be reduced through optimization with EUD optimization compared to dose-volume.