Fifty-six patients, selected by clinical criteria, underwent angiography for suspected acute mesenteric ischemia. Twenty-nine patients subsequently did not have mesenteric ischemia and had negative arteriograms. Twenty-seven patients had mesenteric ischemia: arterial thrombosis (three), arterial embolus (seven), venous thrombosis (five), vasculitis with thrombosis (one), and nonocclusive ischemia (11). Of these 27 patients, 12 (44%) received intraarterial vasodilator infusions. Overall, 13 (48%) of the 27 patients survived their hospitalization, including five (45%) of 11 with nonocclusive ischemia. This experience confirms that nonocclusive ischemia is the most common form of the disorder diagnosed by angiography. Most patients with mesenteric ischemia are candidates for intraarterial vasodilator therapy. Early angiography in patients with suspected acute mesenteric ischemia permits early diagnosis and differentiation between occlusive and nonocclusive types. Interventional infusion therapy may improve survival.