The midcalf muscles of eight patients who had peripheral arterial occlusive disease were evaluated by exercise MRI before and after bypass surgery or percutaneous transluminal angioplasty. MRI showed a high intensity of these muscles, especially the posterior muscles, after exercise in all patients before intervention. The mean T 2 relaxation time was maximal immediately after exercise (tibialis anterior, T 2 = 30.8 ms; soleus, T 2 = 36.2 ms; gastrocnemius, T 2 = 32.8 ms) and then gradually decreased to the preexercise level. The difference in the T 2 relaxation time of the soleus between immediately after exercise and at rest was smaller along with improvement of ankle pressure indices (API) after successful intervention (mean T 2 difference: 4.91 and 0.72 ms (p < .001); mean API: 0.54 and 0.86 (p < .001) before and after intervention, respectively). The mean resting midcalf T 2 relaxation time was significantly higher after intervention (tibialis anterior, T 2 = 28.4 and 29.5 ms (p < .05); soleus, T 2 = 31.4 and 32.9 ms (p < .05); gastrocnemius, T 2 = 29.5 and 31.1 ms (p < .01) before and after intervention, respectively). T 2 relaxation time may be a useful quantitative parameter in peripheral arterial occlusive disease as well as in other muscle studies.