Background: Extended D3-mesenterectomy for right-sided colon cancer, removes all tissue around the superior mesenteric vessels beneath pancreas leading to transection of superior mesenteric plexus. In a previous study, the denervation was associated with 0.48 more stools/day. The study aims are to examine how presence of arterial branches proximal to the dissection area, gender and prolonged observation time after surgery affect bowel function following denervation. Methods: The study compares bowel function and Quality of Life in two groups undergoing right colectomy with extended D3-mesenterectomy and traditional D2-mesenterectomy. For further comparison, the denervated group was divided into groups with and without arterial branches arising proximal to the denervation. Instruments used were Gastrointestinal Quality of Life Index (0–144; 144= best) (GIQLI), Diarrhea Assessment Scale (0–12; 0= best) (DAS) and 3 additional questions (Ability to postpone defecation, night defecation, degree of distress). A second interview with prolonged observation time was performed for patients with abnormal bowel habits, defined as a) having 4 or more stools/day or b) being much or very much bothered. Results: Eighty-three D3-patients and 61 D2-patients, comparable for age and sex with shorter follow-up in the D3-group. In the D3-group 67 patients (80.7%) had one or more arteries proximal to the denervation. Sixteen patients (19.3%) had no proximal arteries. Regression analysis (correcting for confounding factors) revealed 0.30 (P=0.012) lower consistency score (increased consistency) and 0.27 (P=0.096) fewer stools/day in the D2- than the D3-group. DAS subscores, DAS, GIQLI and GIQLI-subscales revealed no differences between the groups. Within the D3-group, the estimated differences between patients with and without proximal arteries (adjusted for age, gender and time between surgery and interview) were significant for DAS and subscores; DAS: −1.526 (P=0.012), stool frequency: −0.653 (P=0.007), stool consistency: −0.432 (P=0.054), stool urgency: −0.595 (0.009). Negative scores represent lower (better) scores in the group with proximal arteries. GIQLI scores and subscales showed no difference. When genders were compared separately, the T-test revealed significantly lower (better) DAS and subscores for D2-females than D3-females, a difference not found in the male group. When controlled for observation time and age (regression) the difference disappears. A second interview with prolonged observation time (1. interview: 15.1 months, 2. interview: 56.4 months) for patients with abnormal bowel function reveals reduced (better) Extended DAS score (DAS + additional questions) in 8 of the 10 patients interviewed. 7 had no longer abnormal bowel function. Conclusions: D3-patients without arteries proximal to the nerve transection have significantly higher (worse) DAS-scores and subscores. The allover difference between the D2 and the D3 patients is small and only significant for consistency. Normalizing of the bowel function takes longer than assumed and continues for months and even years. Women are less able to compensate for the altered bowel habits during normalization.