Transcutaneous tissue oxygen tension (PtcO2) was evaluated as a noninvasive diagnostic test for peripheral arterial insufficiency; PtcO2 was measured at rest, during exercise, and following exercise at three leg sites in 36 controls and 138 patients with exercise-induced leg pain. Resting foot PtcO2 differed significantly in controls and in patients with rest pain (32/138) and was 60.1 +/- 6.82 mmHg and 3.66 +/- 3.68 mmHg, respectively (p less than 0.001). Abnormal resting PtcO2 values occurred in 80% of claudicants (85/138) and 20% had normal values. However, all vascular claudicants exhibited a decline in PtcO2 following exercise, a finding that distinguished them from controls (p less than 0.001). The PtcO2 values in 21 patients who were subsequently shown not to have vascular disease did not differ significantly from controls (p greater than 0.5). Comparison with angiograms (48) showed that PtcO2 following exercise had a 100% sensitivity and specificity in detecting the presence of arterial disease. If resting values alone are considered, sensitivity falls to 77%. This study demonstrates that measurement of PtcO2 at rest and particularly after exercise is a simple and sensitive noninvasive diagnostic test for peripheral arterial insufficiency. This test will serve to distinguish between vascular and other causes of exercise-induced leg pain.