Background/aims: To determine the sensitivity and specificity of multidetector computed tomography-based virtual colonoscopy for colorectal polyp detection by using conventional colonoscopy as the reference standard. Methods: 48 patients with high risk for colorectal cancer underwent virtual colonoscopy followed by conventional colonoscopy. Examination results were compared with conventional colonoscopy, which served as the gold standard. Results: Virtual colonoscopy correctly depicted 19 of 22 polyps (sensitivity, 86%) that were detected in conventional colonoscopy. All 4 polyps that were greater than 10 mm in size (100%), 6 of 7 polyps 6-9 mm in size (85%), and 9 of 11 polyps 5 mm in size or smaller (81%) were correctly depicted with virtual colonoscopy. Virtual colonoscopy had an overall sensitivity of 86% and specificity of 98%. Conclusion: Multidetector computed tomography-based virtual colonoscopy has excellent sensitivity for the detection of clinically important colorectal polyps.