Background: Transanal endoscopic microsurgery (TEM) is a minimally invasive technique for the local resection of benign and stage T1 rectal lesions in selected patients, associated with lower morbidity and mortality rates than open surgery. We present our initial results and assess whether experience influences outcome after TEM. Methods: This was a prospective descriptive survey. All patients undergoing TEM for tubulovillous adenoma or carcinoma between 2002 and 2007 were included. Results: A total of 105 patients were included. Median age was 68 years. Median distance of the lesion from the anal verge was 7.0 cm; median operating time was 90 min. In 10 patients, the peritoneum was opened. Six procedures were converted to (low) anterior resections. Postoperative staging revealed 77 tubulovillous adenomas, 22 stage T1, 5 stage T2 and 1 stage T3 carcinomas; tumor resection was radical in 86%. The postoperative complication rate was 7.6%. Length of hospital stay, operating time and complications significantly diminished over time. After a median follow-up of 27 months, 8 recurrences occurred (7.6%). Conclusion: TEM is a safe technique with low morbidity and recurrence rates. Over time, experience leads to a reduction in operation time, lenght of patients’ hospital stay and complication rate. TEM remains the treatment of choice for benign lesions and stage T1 rectal carcinomas in selected patients.