On experience of 1991 patients authors have studied the opportunities of ultrasonic diagnostics of colorectal cancer and preoperative sonographic staging of this process. The ultrasonic diagnosis of rectal tumors are confirmed at 117 patients (5.9%). Liver metastasises are revealed and verified at 31 patients (26.5%) with the confirmed diagnosis of rectal cancer. Sensitivity of a method at staging of rectal tumors was 95.6%, specificity— 40.0% and accuracy— 85.7%, and at revealing of the metastasises in pararectal lymph nodes sensitivity was 95.2%, specificity— 95.0% and accuracy— 92.3%. The conclusion is, that transabdominal ultrasonography of rectum and liver is non-invasive and informative method of screening — diagnostics of rectal cancer and the metastasises. The diagnostic algorithm developed by authors allows to determine the indications to the operative treatment in the preoperative period and to lower rectal cancer relapses.