Retrospective clinical study of patients with rectal tumors treated by transanal endoscopic microsurgery (TEM) using Ultracision.From 1997-2006 54 patients were treated by excision of the rectal tumors situated in the middle and distal portion, using the harmonic scalpel. We treated 25 male (range 40-76 years) and 29 female (range 46-80 years) patients. Tumors were benign or well or moderately differentiated carcinomas in stage T1N0M0 or T2N0M0. Excision was done by Ultracision (UltraCision, Ethicon Endo-Surgery) to all patients. Preoperative examinations were: colonoscopy, biopsy, tumor markers, CT, transanal ultrasound, pelvic NMR, gynecological exam in females. The tumors were excised by harmonic scalpel after submucosal infiltration of adrenalin (1: 200 000) and 2% lidocaine.There was no morbidity or mortality in this group of patients. Histopathology was: Adenoma tubovillosum in alteratio maligna 20, adenocarcinoma (T1N0M0) 6, (T2N0M0) 8, adenocarcinoma with lymphatic vessels and perineural spaces invasion 1, adenoma villosum 12 and adenoma tubulare 7. After surgical treatment 8 patients underwent adjuvant radiotherapy. There was no local recurrence during this period.TEM is a method of choice in the treatment of rectal benign tumors and malignant tumors in stage T1N0M0, grade 1 and 2. Harmonic scalpel provides a safer, easier, and more precise surgical section through clean, bloodless and better visualized operative field.