This study was designed to examine the plasma levels of adiponectin as well as markers of inflammation and endothelial function in peripheral arterial occlusive disease (PAOD), and to investigate the pathophysiological significance of adiponectin in this disease. Eighty-eight subjects with (n=40) and without PAOD (n=48) were enrolled. Multiple regression analysis including age, sex, body mass index, hypertension, diabetes, triglycerides, high-density lipoprotein cholesterol, creatinine, soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cellular adhesion molecules-1 (sVCAM-1), von Willebrand factor, and high-sensitive C reactive protein (Hs-CRP) showed that adiponectin concentration was significantly lower in PAOD subjects (PAOD: 7.9+/-0.7 microg/mL versus without PAOD: 9.5+/-0.6 microg/mL, F=4.94, p<0.03). Furthermore, concentrations of adiponectin (F=8.5, p<0.01) as well as sICAM-1 (F=5.8, p<0.02), sVCAM-1 (F=5.9, p<0.02), and Hs-CRP (F=3.8, p=0.05) were independently associated with ankle-brachial index. In 27 subjects (10 with PAOD and 17 without PAOD), adiponectin levels in the femoral artery and saphenous vein were measured. A significant step-up of adiponectin from the artery to the vein was observed in subjects without PAOD (+13.0%, p<0.01), but not in subjects with PAOD (+0.4%, NS). Plasma adiponectin as well as Hs-CRP were followed before and after percutaneous transluminal angioplasty (PTA) in eight patients. Adiponectin showed a tendency to decrease after PTA (day 6, -30.6%), although Hs-CRP significantly increased. Adiponectin is decreased in patients with PAOD in proportion to the severity of the disease. Adiponectin concentration could be a marker of the existence of atherosclerosis, and measurement of its concentration may be helpful in assessment of the progress of atherosclerosis.