Clinical observations confirming the presence of critical zones in blood supply of the intestine are presented. It was shown that exclusion of the vessels of the right half of the colon is responsible for the disturbance of blood supply in the terminal part of the small intestine. Suture bands should be displaced to the level at which the intramural pressure ensures the viability of the intestine in the anastomosis zone. This should be taken into account in resections of the transverse colon, left-side hemicolectomy, abdominal resection and frontal resection of the rectum.