Blood gases, electrolytes, metabolites and enzymes were studied in the venous effluate from the leg and in the systemic blood of 8 patients suffering from obliterating arteriosclerosis, during and after reconstructive arterial surgery. The common femoral artery was clamped for 50 to 180 min. Marked hypoxia and acidosis, together with a rise in lactate, phosphate and creatinine concentrations were found in the popliteal vein samples. Changes in the electrolyte concentrations were also observed. The rises in K+ and Mg++ were most pronounced. None of the changes wre correlated to the occlusion time and only small inter-individual variations were recorded. Only minor systemic change occurred after restoration of blood flow. The maximum postoperative CPK-activity, however, was closely correlated to the occlusion time, but judging by the level of this activity the actual muscular damage caused by the ischaemia was moderate, even after prolonged arterial clamping.