Adiponectin is an adipose-derived cytokine, and it is suggested that hypoadiponectinemia increases the prevalence of ischemic heart disease (IHD). The present study was undertaken to determine serum adiponectin levels in patients with arteriosclerosis obliterans (ASO) and IHD. Forty-nine patients with ASO and 49 age-, sex-, and body mass index-matched control subjects were examined. The diagnosis of ASO was derived from an ankle brachial index of less than 0.90 and stenotic or obstructive change in angiogram. Ischemic heart disease was diagnosed by ischemic or stenotic change in ECG, treadmill, or coronary angiogram. Serum adiponectin level was 8.6 +/- 0.9 microg/mL in the patients with ASO, a value significantly less than that of 12.4 +/- 1.0 microg/mL in the control subjects ( P < .01). Next, we subgrouped the subjects into 4 groups according to the presence of ASO and IHD. Serum adiponectin levels were 9.4 +/- 1.5 and 10.2 +/- 1.6 microg/mL in the subjects with ASO (n =23) and those with IHD (n = 13), respectively. It was further reduced to 7.9 +/- 1.2 microg/mL in the subjects having both ASO and IHD (n = 26), a value significantly less than that of 13.2 +/- 1.4 microg/mL in the control subjects (n = 36; P < .05). Serum high-density lipoprotein cholesterol was significantly less in the subjects with ASO than in the control subjects (42.1 +/- 1.7 vs 48.5 +/- 2.0 mg/dL; P < .05), but there were no differences in blood pressure, total cholesterol, low-density lipoprotein cholesterol, triglyceride, and uric acid levels. The present results indicate that a reduction in serum adiponectin level is associated with the prevalence and magnitude of systemic atherosclerosis including IHD and ASO.