Background and aims Stenotic colorectal carcinoma impending obstruction (SCRCIO) is a frequently encountered situation complicating 10% to 19% of colorectal cancers. This group of patients cannot undergo complete colonoscopic assessment. The aim of this study is to examine the accuracy of computed tomographic colonography (CTC) as preoperative assessment of the colon of patients with SCRCIO and to measure the effect on the surgical decision. Materials and methods This was a prospective study, from September 2009 through December 2012, on a cohort of symptomatic adult patients with SCRCIO. Patients underwent CTC evaluation after failed conventional colonoscopy (CC), followed by a follow-up endoscopic examination 3–6 months after surgical treatment. Results Twenty-nine patients with an average age of 55 were included in this study; the majority of stenotic masses were located in the sigmoid colon. Preoperative CTC matched the colonoscopy location of the stenotic masses (17 patients). CTC sensitivity per stenotic lesion detection was 100% and 92.5% for the location. Sensitivity was 100% for synchronous lesions, and CTC changed surgical plan in 17% of the patients. Conclusion CTC presented high sensitivity, specificity and accuracy for the identification of colonic lesions of any size. Preoperative CTC may possibly become the diagnostic procedure of choice for SCRCIO patients. It enables surgeons to evaluate the entire colon, minimizing the possibility of surgical re-intervention if there is a finding of synchronous neoplastic lesions at postoperative follow-up endoscopy.