In intestinal anastomoses, local blood flow is one of the most important factors contributing to the success of the healing process. While submucosal local blood flow is maintained better in the colon than in the small intestine, the incidence of anastomotic leakage is higher in the former than in the latter. To resolve this conflict, we have examined differences in the reactivity of the intestinal segments toward the application of tension. Anastomosis was performed with a stapler on the jejunum, ileum, and colon of experimental dogs. The anastomotic sites were subjected to tensile loads applied in incremental steps to measure and compare local blood flow, measured by the hydrogen clearance method, in the submucosal layers of the anastomoses in these intestinal segments. The results of these comparative evaluations indicate that, at a tensile stress level of more than 4 g/mm2, local blood flow in the colon is significantly smaller than that in the jejunum and ileum. These findings were corroborated by microangiographical observations carried out during stress application. The microangiographical data suggest that the rate of filling of the contrast medium is lower with colonic anastomosis than with jejunal and ileal anastomoses. In addition, the intraluminal pressure of the colon was higher than that of the small intestine during the induced peristalsis. The different sensitivity of the local microcirculation systems of the intestinal segments to tension may thus be considered one of the factors accounting for the higher incidence of clinical suture failure in colonic than in small intestinal anastomoses.