Abstract: To investigate the diagnostic value of spiral CT and ultrasound for colon cancer. Methods: Preoperative spiral CT and ultrasound diagnoses in 65 colon cancer cases, of which 29 were also diagnosed with barium enema, were compared with the results of postoperative pathology to further assess the diagnostic values of the CT and ultrasound methods. Results: Spiral CT and ultrasound diagnoses were respectively consistent with the pathology in 55 and 50 of the colon cancer cases, with a diagnostic accordance rate of 84.6% and of 76.9% in the two groups, respectively. The diagnostic results of barium enema in 23 of the 29 cases was consistent with the pathological results, with a diagnostic accordance rate of 79.3%. The results of 64 cases diagnosed by a combined spiral CT and ultrasonography diagnoses were consistent with the pathological diagnosis, with a diagnostic accordance rate of 98.5%. Statistical results indicated no statistical significance among the three methods ( χ2 = 1.257, P > 0.05 ). A statistical significance was obtained in the combined spiral CT and ultrasound examination, compared with any of the three previous methods, that was, with spiral CT: χ2 = 4.424, P < 0.05, with ultrasound: χ2  = 6.985, P < 0.01, and with barium enema: χ2 = 7.379 , P < 0.01. The diagnostic results of surgical pathology confirmed that lymph node metastasis occurred in 34 cases. The results of the preoperative spiral CT, ultrasound, and the combined examination of spiral CT and ultrasound showed that nodal metastasis occurred in 25, 17, and 29 cases, respectively. For the diagnosis of lymph node metastasis, there was significant difference between the spiral CT and surgical pathology, χ2 = 4.626, P < 0.05. Statistical significance was also obtained between the ultrasound and pathological results, χ2 = 12.705, P < 0.005, whereas that between the outcome of the combined method and pathology was not statistically significant, χ2 = 2.186, P > 0.05. Conclusion: There are differences in the diagnoses of colon cancer among spiral CT, ultrasound, and barium enema. However, combined spiral CT and ultrasound diagnoses will significantly improve the diagnostic rate of the cancer and the diagnostic accuracy of lymph node metastasis.