Abstract: Objective To evaluate the acute side effect and efficacy of intensity modulated radiotherapy（IMRT） combined with endocrine therapy for middleadvanced stage prostate cancer. Methods Sixty-seven patients with middleadvanced stage prostate cancer were treated by IMRT combined with endocrine therapy. The regimen was taken as follow: 2.2-2.4Gy per fraction, once a day, five times a week, and DT was 70-75Gy; 0.25g flutamide was administrated orally at the first day of radiotherapy, and three times a day. The side effects and clinical results were observed. KaplanMeier method was used to measure survival. The correlation between the acute radiation of intestinal injury and clinical factors were analyzed. Results There were 21 patients received CR, 37 patients received PR. The follow-up time was 12.5-99.6 months. The follow-up rate was 91.0%. Thirty-nine patients （including death during 5-year follow-up） had a 5-year follow-up. The 3- and 5-year overall survival rates were 89.0% and 89.5%, respectively. The 3- and 5-year diseasefree survival rates were 72.0% and 63.0%. The median survival time of patients with GTV≥141cm³ and patients with GTV＜141cm³ were 36.7 months and 56.9 months respectively, showing significant differences（P=0.037）. The rates of leucocytopenia and decreased hemoglobin were 91.0% and 89.6%. The incidences of acute radiation rectum damage and bladder damage were 100.0% and 95.5%. The GTV volume influenced acute radiation rectum damage（P＜0.05）. Conclusion IMRT combined with endocrine therapy for patients with middle-advanced stage prostate cancer is effective. The acute side effect is tolerable.