Abstract: Objective To evaluate male sexual function in a series of rectal cancer patients randomized to laparoscopic (LS) or open surgery (OS). Methods Between June 2006 and October 2007, a total of 119 patients with rectal cancer were randomly assigned to laparoscopic (n=60) or open (n=59) resection group. All the patients were treated by D3 lymphadenectomy combined with pelvic autonomic nerve preservation (PANP) technique. Sexual function was assessed by International Index of Erectile Function (IIEF) before surgery and on 3, 6 and 12 months after operation. Results Sexual dysfunction rate of LS and OS at 3rd month after operation were 23.3% and 32.3% respectively, and 18.3% vs 27.1% after 6 months, and 11.6% vs 16.9% after 12 months. There were no significant difference between LS and OS in sexual dysfunction rate after surgery. Conclusions Laparoscopic D3 lymphadenectomy combined with PANP is not associated with higher sexual dysfunction rate, and the sexual function after laparoscopic surgery is satisfactory.