99Tcm-Sestamibi has now replaced 201Tl as a cardiac imaging agent. In addition to the myocardial uptake there is also a considerable uptake in the striated muscle, which may be used for analyzing the muscular perfusion. Sixteen patients with intermittent claudication were investigated with 99Tcm-Sestamibi-SPECT (single photon emission computerized tomography) in order to visualize coronary ischemic disease. After the registration of the myocardial perfusion they were also studied regarding their leg muscle perfusion. This was done at rest and during standardized stress test using a bicycle ergometer. In 10 of the patients there was an increase in the isotope uptake in the myocardium from work to rest > 10% reflecting pronounced myocardial ischemia, which, however, was symptomatic in only 4 of the patients. The muscular uptake in the myocardium of 99Tcm-Sestamibi in the thigh increased significantly from rest to exercise (P < 0.01), while it remained unchanged in the calf muscle. There were no significant correlations at rest between the ratio of the right and left systolic blood pressure in the ankles and the ratio between the right and left isotope uptake in the calves, but the increase in the isotope uptake from rest to work correlated with the blood pressure ratio at r = 0.79, P < 0.01 (anterior projection) and r = 0.71, P < 0.01 (posterior projection).