Transanal endoscopic microsurgery (TEM) allows for the resection of large adenomas and early stage cancers in the rectum. The rate of complications and recurrence for malignant tumors compared with benign tumors has been questioned.The objective of our study was to analyze the outcome after TEM procedures for adenomas and cancers with focus on local recurrence and complications.All 280 patients who had a TEM procedure between January 2008 and September 2015 were enrolled in a prospective cohort study. Outcome was described for benign and malignant tumors. Mortality, recurrence, and complications were recorded.Two hundred eighty tumors were treated with TEM, 176 (63%) were benign and 104 (37%) were malignant. Complication rates were significantly different in the 2 groups, 10.8% (n = 19) in the benign and 24.0% (n = 25) in the malignant group (P = 0.003). A significant difference in perforation/penetration to the peritoneal cavity was noted (P = 0.034). There were no significant difference in the recurrence rate of 8.3% (n = 13) in the benign and 9.0% (n = 7) in the malignant groups. Thirty days mortality rates were 1.1% in the benign group versus 1.9% in the malignant. Other complications were noted in 2.8% and 3.8% in the benign and malignant group, respectively.TEM seems to be a safe and viable procedure for removing both benign and malignant lesions from the rectum. TEM offers low mortality and complication rates also recurrence after resection of malignant tumors.