BACKGROUND Intra-peritoneal adipose tissue is recognized as a predictor of metabolic syndrome and may contribute to the risk for cardiovascular disease by the production of adipocytokines, including adiponectin. Nevertheless, there is no knowledge on whether other visceral depots of adipose tissue, including the epicardial fat, have any metabolically active role, including production of adiponectin. OBJECTIVE We sought to evaluate adiponectin protein expression in epicardial adipose tissue in vivo both in patients with severe coronary artery disease (CAD) and in subjects without CAD. METHODS Twenty-two patients were enrolled for the study. We selected 16 patients who underwent elective coronary artery bypass graft surgery for critical CAD, 5 who underwent surgery for valve replacement and 1 for correction of an interatrial defect. Epicardial adipose tissue biopsy samples were obtained before the initiation of cardiopulmonary bypass. Adiponectin protein level in epicardial adipose tissue was evaluated by Western blotting. RESULTS Adiponectin protein value, expressed as adiponectin/actin ratio, in epicardial adipose tissue was significantly lower in patients with severe CAD than in those without CAD (1.42 +/- 0.77 vs 2.36 +/- 0.84 p = 0.02, 95% CI 0.64-1.74). CONCLUSIONS This study showed for the first time that human epicardial adipose tissue expresses adiponectin. Adiponectin expression is significantly lower in epicardial fat isolated from patients with CAD.