The blood-flows in the inferior mesenteric artery (IMA) and internal iliac arteries (IIAs) among patients operated on for abdominal aortic aneurysm (AAA) need to be characterized. The blood-flows in the IMA and IIAs were measured with transit-time flowmeter in 26 consecutive patients who underwent open surgery for AAA. The blood-flow of the superior mesenteric artery was not studied. The IMA could be measured in 25 patients, was occluded at its origin from the aorta in ten, one of whom had a collateral blood-flow of 31 ml/min distal to the occlusion. In 16 with a measurable IMA blood-flow, the median blood-flow was 26 ml/min (range 14-57 ml/min). In all 25 patients the median bloodflow in the IMA was 18 ml/min. The IIAs were occluded bilaterally in two patients and unilaterally in five. The median blood-flow in the right IIA was 111 ml/min (0-268), in the left 94 ml/min (0-340). The median blood-flow in the three studied arteries was 256 ml/min (0-506). The median proportion of the blood-flow originating from the IMA, compared to the blood-flow of all three arteries, was 10% (0-100%). One patient with no flow in any of three arteries developed colonic ischaemia. The relative blood-flow of the IMA, in relation to that of the IIAs, is small in most patients. In patients with IIA aneurysms or simultaneous occlusive disease, blood-flow measurements may' be valuable for clinical decision-making.