Objective To evaluate transsphincteric operation (Mason operation) for rectal tumors.Methods Retrospective study was used to analyze the experience of Mason operation for 150 patients with mid and lower rectal tumors between Aug 1990 to Dee 2008. Results There were villous adenoma in 75 cases,early rectal cancer in 48 and advanced rectal cancer in 9,submucosal carcinoid nodule in 23.Of the 126 rectal tumor patients,120 underwent partial rectectomy,6 underwent segmental rectectomy.Seventeen out of the 21 rectovaginal fistula or rectourethral fistula cases underwent successful one-stage repair.Six patients(4%)developed wound infection.Five patients(3.3%)were complicated with recto-cutaneous fistula.Two patients(4.3%) suffered from local recurrence in 46 followed up early staged rectal carcinoma with a five-year survival rate of 84.5%(39/46).On discharge from hospital no patient suffered from incontinence.Conclusion Mason operation is satisfactory with good exposure and simple access to the rectum,which Was suitable for those lesions that could be locally resected on mid and lower rectum.