An investigation of the information value of modern radial methods of diagnostics (endorectal and intraoperative sonography, spiral computed and magnetic resonance imaging) and Power Shape program for three- dimensional modeling in 150 patients with rectum cancer has shown their significance in the assessment of prevalence of the tumor process, invasion of the tumor into the rectum wall, its spreading in the intestinal wall, involvement in the tumor process of the pararectal fat and adjacent to the rectum organs of the small pelvis, the presence of signs of metastases to the regional lymph nodes. These methods of X-ray analyses and three- dimensional computed modeling of the tumor process of the rectum facilitate preoperative decision on the adequate volume of surgery.