The use of transcutaneous oxygen tension (TCpO2) measurements to objectively and noninvasively diagnose peripheral arterial occlusive disease (PAOD) and to aid in the planning of vascular surgery was investigated. Thirty-two normal subjects and 100 patients with PAOD were studied. TCpO2 values decreased with age; when normalized by measurements on the chest, they did not. Absolute and normalized values of TCpO2 were equally effective in identifying the presence of PAOD and accurately characterized different degrees of severity (claudication vs. rest pain vs. impending gangrene; p less than 0.001). This was true even in diabetic patients, in whom tests based on hemodynamic function were less reliable. Healing of amputations was observed when TCpO2 greater than or equal to 38 mm Hg either preoperatively or after reconstruction; failure to heal in the absence of infection was associated with TCpO2 less than or equal to 38 mm Hg. The need for revascularization was associated with TCpO2 less than 30 mm Hg. A similar distribution of TCpO2 values was associated with success vs. failure of ulcer healing. TCpO2 is a useful complement to standard hemodynamic tests in the diagnosis and management of PAOD and, in addition, provides some distinct advantages.