The role of adiponectin and epicardial adipose tissue in coronary artery disease (CAD) is a subject of debate. Whether plasma adiponectin concentration in the coronary circulation is locally modulated by the epicardial fat is still unexplored. We evaluated the hypothesis whether intracoronary plasma adiponectin levels are related to adiponectin expression in epicardial adipose tissue in vivo in patients with CAD and without CAD (non-CAD). We examined 12 patients with CAD who required CABG and 10 patients with non-CAD who underwent cardiac surgery for valve replacement. Plasma levels of adiponectin were measured in peripheral vein circulation and in left coronary artery (LCA) during coronary angiography. Epicardial adipose tissue biopsy for adiponectin protein extraction was performed during cardiac surgery in both CAD and non-CAD subjects. Adiponectin protein expression in epicardial adipose tissue was lower in patients with CAD than in those with non-CAD (0.45+/-0.4 vs. 1.1+/-1.0, p<0.05). LCA plasma adiponectin levels significantly correlated with epicardial adipose tissue adiponectin protein expression (r=0.68, p=0.02) in all subjects. Peripheral adiponectin levels and epicardial fat adiponectin protein expression were the best correlates of LCA adiponectin, r (2)=0.49, p<0.01, p<0.05, respectively). Our study showed that intracoronary adiponectin levels reflect systemic adiponectin levels. Epicardial adipose tissue could partially contribute to adiponectin levels in the coronary circulation.