Background: This study was designed to determine the incidence and patterns of sexual dysfunction after curative radical resections (CRR) with or without extended systematic lymph-node dissection (ESLND) for rectal cancer Material/Methods: A total of 91 patients with rectal cancer were reviewed with respect to surgical procedures and postoperative sexual functions using the International Index of Erectile Function (IIEF), a 15-item self-administered questionnaire. CCR (abdomino-perineal resections or sphincter-saving anterior resections) was performed in 78 patients (Group I) and ESLND plus CRR in 13 patients (Group II), and sexual functions were also evaluated in the colostomy and non-colostomy subgroups. Results: In the postoperative period, the five domains of IIEF scoring decreased significantly from the preoperative scores in both groups (p<0.05), but the postoperative decreases were not significant between groups I and II (p>0.05). Having a permanent colostomy decreases IIEF scores in all colostomized patients. Conclusions: CRR and CRR+ESLND both decrease sexual function and lymph-node dissection is not considered to have any additive effect on this decrease. In addition to standard surgery, anxiety about having a malignant disease and permanent colostomy may play an important role in male sexual dysfunction.