The regional uptake of Thallium-201 is correlated with the regional distribution of cardiac output in the myocardium as well as in skeletal muscle. Thallium-201 perfusion scans will detect peripheral occlusive arterial disease (POAD) as well as coronary heart disease (CHD). In a prospective study we examined POAD patients and CHD patients by both myocardial and leg stress scintigraphy. In normals the uptake ratio of both calves was 1.03 +/- 0.05 (mean +/- SD), while in all patients with proven POAD the ratio was higher than 1.2. In 12 of 16 patients with myocardial infarction the high ratio indicated a coincidence of POAD and CAD, confirmed by other techniques in all but one patient. In patients with suspected CHD there was an increased ratio in 8 of 21;6 of these patients also had an abnormal myocardial stress scan, while there were only 4 abnormal scans in the 13 patients with normal leg uptake. In 19 of 26 patients with known POAD the myocardial stress scan was abnormal, indicating CHD in 75% of this group. This was confirmed in most patients by coronary angiography. The combination of myocardial and leg stress scan can be carried out without further radiation exposure to the patient and in a few minutes. It is a new approach to determine the possible coincidence between POAD and CHD; it should be performed in all patients referred for TI-201 myocardial stress scintigraphy.