Ligation of the inferior mesenteric artery (IMA) during sigmoid colectomy may cause sympathetic denervation of the rectal stump. The purpose of our study was to investigate the functional results after sigmoid resection following ligation or preservation of the IMA. We prospectively analysed 44 patients (21 female and 23 male, mean age 60.6 +/- 11.79 years) with sigmoid tumour. Sigmoid colectomy with preservation of the IMA was performed in 21 patients, and ligation of the IMA with sigmoidectomy was carried out in 23 patients. Bowel function follow-up was performed by use of questionnaires: standardized functional questionnaire, constipation-specific, and incontinence scales before, 6 and 12 months after surgery. The quality of life was measured by means of the Fecal Incontinence Quality of Life (FIQL) scale. After sigmoid colectomy with division of the IMA, patients presented with a higher rate of fecal incontinence and increased stool frequency compared with patients after sigmoid resection with preservation of the IMA. Deterioration of FIQL was also observed in patients with ligated IMA. Preservation of the IMA during sigmoid colectomy in selected patients lowers the frequency of postoperative impaired anorectal function.