Postischemic calf volume and blood flow were recorded with mercury strain gauge in normal and arteriosclerotic legs. Constant maximal volume-flow relationship was not demonstrated. Inverse relationship, however, was found between peak flow and peak volume time. Peak volume time was always over 20 seconds in symptom-giving femoral artery obstructions and under 20 seconds in normal legs and in legs with symptom-free diffuse arteriosclerosis. Peak volume time is therefore a functional index of the circulatory condition with femoral artery obstructions. Peak flow time was occasionally normal (zero) with symptom-giving femoral artery obstructions and is thus a less reliable index.With isolated aorto-iliac obstructions, peak volume time was never largely increased, whereas combined aorto-iliac and femoral artery obstructions nearly always showed a large increase. A merely small increase with aorto-iliac obstructions therefore suggests patency of the femoral artery.