Background : The purpose of this study was to evaluate the usefulness of hydrocolonic sonography (HUS) in local staging of colorectal cancer. Methods : Thirty patients with colorectal cancer underwent HUS for clinical TNM staging before operation and then the preoperative staging was correlated with postoperative histological stage. Results : All cases were correctly localized by HUS. The accuracy of depth of invasion (T staging) was 70% in overall cases. When divided into colon and rectal cancer, T staging was more accurate in colon cancer (88%), however, less accurate in rectal cancer (46.1%). The accuracy was higher especially in aspect of pericolic fat infiltration (93%). In N staging, the accuracy was 60% in overall cases, 71% in colon cancer and 46% in rectal cancer, respectively. The accuracy of N staging by HUS were somewhat poor on the whole due to technical properties. Conclusion : HUS is very valuable with respect to T staging, especially in colon cancer rather than in rectal cancer. N staging was somewhat doubtful in both. Because HUS is easy, noninvasive, and readily available at any place, it would be useful method for local staging colon cancer, especially T staging.