Abstract: Objective: To investigate the applicable value in diagnosis and preoperative staging of the colorectal carcinoma by CT Colonography (CTC). Methods: CTC was performed for 33 patients who were suspected of colorectal carcinoma. The results of CTC were compared with those of pathological examination. Results: Among 22 patients who were diagnosed as the colorectal carcinoma by CTC, 20 were pathologically confirmed. The diagnostic sensitivity and specificity was 100% (20/20) and 84.6% (11/13) respectively. The accuracy of diagnosis for typing the carcinoma pathologic patterns was 90% (18/20). The sensitivity and specificity were 100% in the type of masses both, and were 77.8% and 100% in the type of infiltration and 100% and 85.7% in the type of ulceration. The accuracy of staging carcinoma with Duke was 75%. The sensitivity and specificity were 100% and 94.1% in Duke's A, 80% and 73.3% in Duke's B, 60% and 100% in Duke's C and were 71.4% and 100% in Duke's D, respectively. Conclusion: CTC examination could provide miscellaneous diagnostic information and can be of great value not only for accurate diagnosis of the colorectal carcinoma but also for preoperative staging of the disease.