Objective To investigate the comprehensive treatment of Crohn's disease complicated with anal fistula.Methods The clinical data of 33 patients with Crohn's disease complicated with anal fistula who were admitted to the Sixth Hospital of Sun Yat-Sen University from June 2007 to April 2011 were retrospectively analyzed.According to the range of the disease,surgical,medical and combined treatment were applied.Surgical treatment included thread-drawing drainage,fistulectomy,incision and drainage of the perianal abscess and enterostomy.Medical treatment include 5-aminosalicylic acid,immunosuppressive therapy,glucocorticoid,tumor necrosis factor monoclonal antibodies.All the patients were followed up till August 2012.The Crohn's disease activity index (CDAI) and perianal Crohn's disease activity index (PDAI) before and after treatment were analyzed using the independent sample t test.Results Of the 33 patients,22 received surgical and medical treatment,7 received surgical treatment,and 4 received medical treatment.The anal fistula was healed in 18 patients after the initial treatment (3 of them did not receive surgical treatment),and the mean closure time of the fistula was (3.2 ± 2.6) months (range,1-12 months) ; the condition of 8 patients was improved ; 4 patients suffered from fistula persistence ; anal fistula recurrence was observed in 6 patients,and the time for anal fistula recurrence was (35 ±56)months (range,5-148 months).The preoperative CDAI and PDAI of the 33 patients were 166 ± 100 (range,7-361) and 9.2 ± 2.6 (range,5-16),and the postoperative CDAI and PDAI of the 33 patients were 83 ± 53 (range,0-212) and 2.7 ± 3.1 (range,0-11).There were significant differences between the pre-and postoperative CDAI and PDAI (t =4.20,8.92,P ＜0.05).Of the 12 patients who were failed in the initial treatment,the anal fistula was healed in 3 patients after the treatment,and the condition of the other 9 patients remained the same.Of the 6 patients with anal fistula recurrence,5 received reoperation (4 were healed and 1 remained the same after the treatment) and the fistula of 1 patient who received medical treatment was not healed.At the end of the follow up,the anal fistulas of 20 patients were healed,and 10 remained the same.Conclusions There is no standard treatment for Crohn's disease complicated with anal fistula,surgical treatment combined with medical treatment is important for the treatment of Crohn's disease complicated with anal fistula.Surgical procedures should be chosen carefully according to the condition of the patients.