OBJECTIVE: Inflammation has been suggested as a risk factor for the development of atherosclerosis, while some components of metabolic syndrome X have been related to inflammatory markers. We hypothesized that adipocyte secreting protein, adiponectin and leptin, for which have been demonstrated an association with metabolic syndrome X and coronary artery disease, may be associated with inflammatory markers in nondiabetic humans. DESIGN AND METHODS: We measured high-sensitivity C-reactive protein (hs-CRP), as an inflammatory marker, and adiponectin and leptin concentrations in 384 nondiabetic Japanese women (mean+/-s.e.m. age 53.6+/-0.8 Years, body mass index (BMI) 23.0+/-0.2 kg/m(2)) undergoing measurement of markers of metabolic syndrome X. RESULTS: The women who had a low-grade hs-CRP elevation (>2.0 mg/l) were significantly older and had higher BMI, body fat mass (BFM), total cholesterol (TC), triglyceride (TG), atherogenic index (AI=(TC-HDLC)/HDLC), where HDLC is high-density lipoproten-cholesterol), fasting blood glucose and leptin concentrations before and after adjustment for BMI or BFM, while lower HDLC and adiponectin concentrations before and after adjustment compared with women with normal CRP levels (<0.5 mg/l). BMI, BFM, TG, AI and leptin before and after adjustment were found to be correlated with hs-CRP levels, while HDLC and adiponectin before and after adjustment were inversely correlated (all P<0.0001). hs-CRP was independently associated with white blood cell count, blood urea nitrogen and AI and inversely with adiponectin/BFM in the stepwise regression analysis model. CONCLUSIONS: These data demonstrate a significant decrease in plasma adiponectin in low-grade chronic inflammation, and suggest that there is an important linkage between inflammation/adipose tIssue/atherosclerosis.