INTRODUCTION: Transanal endoscopic microsurgery for rectal adenomas is safe and has low recurrence rates. However, the feasibility of the procedure for all rectal adenomas is unclear. This issue was investigated prospectively. METHODS: From 1996 to 2007, 353 consecutive rectal adenomas were evaluated according to a standard protocol. Transanal endoscopic microsurgery was intended in all rectal adenomas. RESULTS: The median diameter was 3 cm and median distance was 8 cm. The peritoneum was opened peroperatively without any adverse effects in 8.7 percent. The conversion rate was 9.6 percent, with an alternative local procedure performed in 4.2 percent and a transabdominal procedure performed in 5.4 percent. Conversion rate correlated with the distance of the tumor (P = 0.007) and the operating surgeon's level of experience (P = 0.004). The median operation time was 45 minutes. Operation time correlated with specimen area, experience, and operating surgeon (all P < 0.001). All rectal adenomas were excised in one piece. Complete margins were observed in 85 percent. Rectal adenomas with incomplete margins were larger (P < 0.001) and were located more proximally (P < 0.001). Morbidity was 7.8 percent and mortality 0.6 percent. The median hospital stay was four days. The median follow-up was 27 months. The recurrence rate at three years was 9.1 percent. The median time from operation to recurrence was 12 (range, 4-54) months. Resection margin status was a predictor of recurrence, with 6.1 percent recurrence in cases of complete margins and 25.2 percent in cases of incomplete margins (P < 0.001). CONCLUSIONS: For nearly all rectal adenomas, transanal endoscopic microsurgery is safe, feasible, and has excellent results.