Objective To investigate the effects of Houpupaiqi mixture on the recovery of gastrointestinal function after open gastrointestinal surgery,and evaluate the efficacy and safety of Houpupaiqi mixture.Methods A total of 144 selected patients who underwent open gastrointestinal surgery were enrolled into the multi-center prospective randomized double-blind controlled clinical trial from October 2010 to September 2011.Of the 144 patients,66 were from People's Hospital of Peking University,72 were from Beijing Friendship Hospital of Capital University of Medical Sciences,and 6 were from People's Hospital of Guangdong Province.All the patients were randomly divided into 2 groups (test group:96 patients,control group:48 patients) at the ratio of 2∶1 according to the random number table.Five patients who did not meet the criteria were excluded from the study,and then there were 92 patients in the test group and 47 patients in the control group.The study was assessed by the ethics committees,and all the patients signed the informed consent form.Houpupaiqi mixture (50 ml) or placebo (50 ml) were administered in the test group and control group at postoperative 16 and 20 hours,respectively.Parenteral and enteral nutritional support were given after pulling out of gastric tube.A standard intravenous analgesia was applied in the 2 groups,and agents which stimulate or suppress gastrointestinal motility were prohibited.The time for the recovery of regular bowel sounds,the first exhaust and first defecation time,and the time of first solid food intake of the 2 groups were recorded.Vital signs were recored before operation and after drug administration.Blood and urinary routine test,hepatic and renal function test,electrocardiogram examination,record of adverse drug event were carried out at postoperative day 6.The time for the indexes above and relevant frequencies were calculated,and the survival curve were drawn by Kaplan-Meier method.All the time points were analyzed using the Log-rank test.The measurement data were analyzed using the t test or rank-sum test,and the enumeration data were analyzed using the chi-square test or Fisher exact probability.Results The median time for the recovery of regular bowel sounds,median time for first exhaust and defecation were 21.4 (20.0,23.7)hours,45.0 (40.0,54.0) hours and 65.5 (54.7,74.0) hours in the test group,and 47.5 (44.0,56.5) hours,91.0 (87.0,93.8)hours,98.0 (94.0,113.5)hours in the control group,there were significant differences between the 2 groups (Log-rank values =21.67,53.15,11.81,P<0.05).The median time of first solid food intake were 72.5 (66.2,110.5) hours of the test group and 116.3 (114.8,117.3) hours of the control group,with no significant difference between the 2 groups (Log-rank value =13.70,P > 0.05).There were no significant differences in the body temperature,respiration,heart rate,systolic blood pressure and diastolic blood pressure before and after medication between the 2 groups (Z =0.03,0.68,0.97,0.22,0.72,P > 0.05).There were no significant differences in the number of patients with abnormal results of blood test,hepatic function,renal function and electrocardiogram between the 2 groups (P > 0.05).No severe adverse event was observed in the clinical trial.Conclusion Houpupaiqi mixture significantly promotes the recovery of gastrointestinal function of the patients who underwent open gastrointestinal surgery with relatively low adverse events. Key words: Digestive diseases ; Gastrointestinal surgery ; Houpupaiqi mixture; Gastrointestinal function ; Postoperative ileus