The authors specify the methods used for measuring teh transcutaneous oxygen pressure (TcPO2), then present the four main advantages of the TcPO2. 1. Although the decision to amputate remains controlled by the clinical evaluation, TcPO2 is useful when one has to choose to preserve or not the heel support or the knee joint, when hesitating on the indication of amputation or the nature of the pain of a stump. Two measurements are crucial: a value of TcPO2 in a decubitus position greater than 30 mmHg at the amputation level seems to guarantee a primary healing, while under 10 mmHg, failure is the rule. 2. Correlations between the Fontaine classification and TcPO2 measured on the fore-foot in decubitus position, show that, at stages I and II, the TcPO2 is not significantly decreased in comparison with the control group (54 +/- 12 mmHg at stage I, 49 +/- 11 mmHg at stage II) and that at stages III and IV, TcPO2 is significantly much lower than at stages I and II and the value of 10 mmHg seems a remarkable threshold defining severe ischemias (12 +/- 15 mmHg at stage III, 3 +/- 5 mmHg at stage IV). 3. A prospective study of 66 arterial disease of the lower extremities cases, at stages II and IV, validated by a TcPO2 measured at the fore-foot in decubitus position less than 10 mmHg, and which could all benefit from reconstructive arterial surgery, is presented.(ABSTRACT TRUNCATED AT 250 WORDS)