Objectives: To determine the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the main radiologic signs on the double-contrast technique in the diagnosis of colorectal cancer. Material and methods: We retrospectively analyzed axial slices and clinical histories of 132 patients of whom 18 (13.64%) were diagnosed with colorectal cancer. Results: The mean age of the patients with colorectal cancer was 61 years; 11 (61.11%) were male and 7 (38.89%) were female. According to Dukes' classification, 1 (5.55%) patient had stage A disease, 3 (16.66%) stage B, 8 (44.44%) stage C, and 6 (33.33%) stage D. We detected polyps in 100% of the images obtained by subtraction and diverticula in 100% of those obtained by addition. The distribution by colon segments was as follows: ascending colon n=2 (11.11%), transverse colon n=4 (22.22%), descending colon n=2 (22.22%), sigma n=6 (33.33%), and rectum n=4 (22. 22%). The diagnostic accuracy of the technique was sensitivity 83.33%, specificity 99.25%, PPV 88.24%, and NPV 97.39%. Conclusions: Colorectal cancer is more common in people older than 50 years. Polyps on subtraction and diverticula on addition are the most common radiologic signs in colorectal cancer when the double-contrast technique is used. The principal radiologic signs on the double-contrast technique are highly sensitive and highly specific for the diagnosis of colorectal cancer. © 2009 ACTEDI. Published by Elsevier España, S.L. All rights reserved.