Patients with a high plasma adiponectin have a poor prognosis in chronic heart failure (CHF). Angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers are reported to increase the plasma adiponectin concentration, but the effect of β-blockers on plasma adiponectin in patients with CHF remains unknown. Blood samples were collected at before and 6 months after administration of carvedilol in 44 CHF patients. The hemodynamic parameters, echocardiography, plasma concentrations of brain natriuretic peptide (BNP), norepinephrine and adiponectin were measured. Six months after treatment, there were significantly decreased plasma concentrations of adiponectin (15.8±1.4 to 11.0±1.1 μg/ml, P< 0.0001), BNP and norepinephrine and increased left ventricular ejection fraction (LVEF). On stepwise multivariable analyses, a higher plasma adiponectin concentration before treatment (rs=-0.561, P< 0.0001) was a significant independent predictor of a greater decrease in adiponectin concentration and the decrease in plasma adiponectin concentration was significantly correlated with the improvement of LVEF (r=-0.561, P< 0.0001). These findings indicate that carvedilol decreases plasma adiponectin concentration and that the decrease in plasma adiponectin is associated with the improvement of LVEF after treatment with carvedilol in CHF patients.(Circ J 2009; 73: 1067-1073)