Abstract: Objective To investigate the clinical effects for prevention of acute radiation proctitis by using Montmorillonite with Kangfuxinye retention enema. Methods One hundred and nine patients who were treating with pelvic radiotherapy were divided into study group（n=55） and control group（n=54）. The control group received conventional preparation： empty bladder at two hours before radiotherapy， drink 500800 ml warm water， hold urine until bladder fill， encourage patients to have high protein， high vitamin diet， and no spicy food during radiotherapy. The study group were given the same preparation as the control group and additionally taken enema which mixed by 30 ml Kangfuxinye， 3 g Montmorillonite and 20 ml 0.9％ NS， as treating with radiotherapy and retention enema at the same time. The incidence of acute radiation proctitis between two groups were compared. Results The incidences of acute radiation proctitis in study group were 18.2％， of which 14.5％ were grade 1， 3.6％ were grade 2 and no grade 3 occured. On the other hand， the incidences of acute radiation proctitis in control group were 53.7％， of which 31.5％ were grade 1， 14.8％ were grade 2 and 7.4％ were grade 3. The differences between 2 groups were statistically significant（P＜0.05）. Conclusion Montmorillonite with Kangfuxinye retention enema combined with radiotherapy has better preventive effects for acute radiation proctitis which induced by pelvic radiation therapy. It has the advantages of convenient operation， no significant toxic and adverse effects， and high tolerance for patients.