Purpose Rectal cancer surgery is impaired by a high rate of postoperative sexual dysfunction cause of frequent nerve injuries The aim of this study was to prospectively evaluate sexual function in a group of male patients after total mesorectal excision (TME) for rectal cancer, using an autonomic nerve sparing technique Methods All patients underwent autonomic nerve preserving TME Sexual function was assessed using the International Index of Erectile Function standardized questionnaire All patients were studied preoperatively and at 3, 6, 12, 18, and 24 months after surgery Results Fifty-one patients with adenocarcinoma of the rectum were enrolled, after excluding 16 patients not sexually active, nine with T4 stage disease and six with metastatic disease, 20 patients were prospectively evaluated The preoperative erectile function (EF) domain score of the International Index of Erectile Function was 24 3 (+/- 4 1) The score of the EF domain was 176 (+/- 7 5), 19 19 (+/- 7 2), 203 (+/- 7 4), 205 (+/- 7 4), and 206 (+/- 7 4) at 3, 6, 12, 18, and 24 months after surgery In the group of patients in which there were no macroscopic damages to the nerves, only two out of 15 (13 3%) developed erectile dysfunction All five patients in whom incomplete pelvic nerve preservation was necessary developed erectile dysfunction Conclusion Our data show that nerve sparing technique can reduce the incidence of sexual dysfunction Unfortunately, the technique is not applicable in every patient Indications and techniques of autonomic nerve preservation are not standardized Controlled trials with long-term follow-up seem to be necessary