A new provocative test for chronic mesenteric ischemia is described, based upon the demonstration of a fall in the intramural pH of the small bowel after introduction of a test meal into the stomach. Intramural pH (pHI) is determined indirectly by tonometry, utilizing a tonometer passed per os. Postoperative assessment of revascularization procedures is also possible by the same technique. Application of the test in an 84-yr-old woman showed good correlation between a preoperative fall in jejunal intramural pH and abdominal pain, and the absence of a fall postoperatively after successful revascularization.