&NA;The effect of subacute large‐bowel obstruction on the mesenteric circulation was studied in a chronic dog model. Colonic obstruction was produced 40 cm distal to the ileocolic sphincter. Five days later, gut blood flow was measured with 15 &mgr;m microspheres, together with hemodynamic and metabolic values. Two other groups provided comparative data: unoperated animals to measure baseline values and sham‐operative controls. With adequate hydration, hemodynamic and metabolic values remained stable in the experimental group. There was a two‐fold increase (P<0.05) in blood flow in the dilated colon proximal to the obstruction site, whereas blood flow to the other organs remained unchanged. These results have relevance for the hemodynamic management and use of primary anastomosis in patients with large‐bowel obstruction. Furthermore, these data might implicate increased local bowel blood flow as a contributory factor to the poorer long‐term prognosis found in patients with large‐bowel cancer presenting with intestinal obstruction.