Objective:To investigate the efficiency,safety,and possible mechanisms of Qingre Buyi Decoction(清热补益煎剂,QBD)in the treatment of acute radiation proctitis(ARP).Methods:This study was a single center,prospective,single blind,randomized,and placebo-controlled clinical trial.A total of 60 patients with ARP was equally and randomly distributed into the control group(conventional treatment)and the combination group(conventional treatment plus QBD).The changes of main Chinese medicine clinical symptoms and signs,including stomachache,diarrhea,mucous or bloody stool before and after treatment, and their adverse reactions were observed after the two-week treatment.Also,D-lactate and diamine oxidase (DAO)levels,hepatic and renal function were measured.Cure rates,effective rates,and recurrence rates were compared between the two groups.Results:The blood levels of both DAO and D-lactate were significantly decreased in the combination group as compared with those in the control group(P<0.05 or P<0.01).All main clinical symptoms and signs were alleviated more significantly in the combination group(P<0.01).The main symptom scores also were significantly decreased after treatment in the control group(P<0.01),except those for mucous or bloody stool(P>0.05).Compared to the control group,the improvements of stomachache,diarrhea, defecation dysfunction,and stool blood in the combination group were significantly better(P<0.05 or P<0.01). For the combination group,the curative rate,effective rate,and recurrence rate was 76.67%,16.67%,and 6.67%, respectively.On the other hand,for the control group,the rate was 53.33%,16.67%,and 30.00%,respectively. The total curative effect was significantly better in the combination group than in the control group(P<0.05). However,the recurrence rate was similar between the two groups(P>0.05).The hepatic and renal function remained normal in both groups(P>0.05).In addition,no severe adverse event was found in both groups. Conclusions:Addition of QBD to the conventional treatment can effectively alleviate the damage of intestinal mucosal barrier function and improve all main clinical symptoms and signs of the ARP.The combination of conventional treatment with Chinese herbal medicine QBD is effective and safe for ARP. Objective: To investigate the efficiency, safety, and possible mechanisms of Qingre Buyi Decoction (in QBD) in the treatment of acute radiation proctitis (ARP). Methods: This study was a single center, prospective, single blind, randomized , and placebo-controlled clinical trial. A total of 60 patients with ARP was equally and randomly distributed into the control group (conventional treatment) and the combination group (conventional treatment plus QBD). The changes of main Chinese medicine clinical symptoms and signs, including stomachache, diarrhea, mucous or bloody stool before and after treatment, and their for negative reactions were observed after the two-week treatment. Also, D-lactate and diamine oxidase (DAO) levels, effective rates, and recurrence rates were compared between the two groups. Results: The blood levels of both DAO and D-lactate were significantly decreased in the combination group as compared with those in the control group (P <0 .05 or P <0.01) .All main clinical symptoms and signs were alleviated more significantly in the combination group (P <0.01). The main symptom scores also were significantly decreased after treatment in the control group (P <0.01), except for mucous or bloody stool (P> 0.05) .Compared to the control group, the improvements of stomachache, diarrhea, defecation dysfunction, and stool blood in the combination group were significantly better (P <0.05 or P <0.01) group, the curative rate, effective rate, and recurrence rate were 76.67%, 16.67%, and 6.67%, respectively.On the other hand, for the control group, the rate was 53.33%, 16.67%, and 30.00% respectively. The total curative effect was significantly better in the combination group than in the control group (P <0.05). However, the recurrence rate was similar between the two groups (P> 0.05). The hepatic and renal function remained normal in both groups P> 0.05) .In addition, no severe adverse event was found in both groups. Conclusions: Addition of QBD to the conventional treatment can effectively alleviate the damage of intestinal mucosal barrier function and improve all major clinical symptoms and signs of the ARP. combination of conventional treatment with Chinese herbal medicine QBD is effective and safe for ARP.