Objective To compare the safety and effectiveness of two methods of perineal dissection in 60 consecutive patients of rectal carcinoma undergoing combined abdominoperineal resection.Methods In this retrospective study from 2007 to 2009, 30 cases underwent Miles' operation using modified method of perineal dissection( MM group) and 30 cases undergoing Miles' operation using classic method of perineal dissection ( CM group). Operative time, accidental tumor ( or rectal) perforation during the procedure, iatrogenic injury to the urethra ( or vagina) and postoperative perineal complications were compared between the two groups. Results The mean perineal operative time was (45±15) min in MM group and ( 70 ± 20) min in CM group respectively ( t = 5. 48, P ＜ 0. 05 ). There were no significant differences in the rate of tumor ( or rectal) perforation and that of urethral (vaginal) injury. There were significant difference in the rate of postoperative perineal complications (χ2=4.01, P＜0.05).Conclusions Modified method of perineal dissection is effective and safe, and this method offers a new approach for the perineal dissection during Miles' operation.