We measured transcutaneous oxygen tension (TcPo2) at a skin temperature of 44 degrees C on 319 limbs in an approximately equal number of nondiabetic and diabetic patients with peripheral vascular disease. Measurements were made above the knee, below the knee (BK), and on the dorsum of the foot. Nondiabetic limbs with leg/foot (the lesser of BK or foot) TcPo2 values below 20 mm Hg were significantly more likely to have ulcers, to have rest pain, or to require an amputation on the limb as compared with limbs with leg/foot TcPo2 values above 20 mm Hg. Patients with more severe symptoms had significantly reduced limb TcPo2 values, and these values were lower at more distal measurement sites. Generally, these results were similar in diabetic and nondiabetic patients without limb ulceration; however, the diabetic patients were more likely to have ulcers in the presence of high limb TcPo2. This observation suggests that ulceration in a substantial proportion of the diabetic patients may have resulted from factors other than insufficient cutaneous tissue oxygen delivery.