High adiponectin concentrations have emerged as an independent risk factor of outcome inpatients with CHF (chronic heart failure); however, modification of adiponectin in CHF patients has not been assessed to date. The aim of the present study was to investigate the effect of exercise training on adiponectin levels in CHF patients. A total of 80 patients with CHF due to systolic dysfunction were included. The effect of 4 months exercise training was studied in 46 patients,whereas the remaining 34 untrained CHF patients served as a sedentary control group. Circulating adiponectin concentrations, exercise capacity, anthropometric data and NT-proBNP (N-terminal pro-brain natriuretic peptide) levels were assessed. Adiponectin levels were significantly higher in CHF patients compared with healthy subjects [9.3 (7.1-16.1) and 4.9 (3.9-8.6) mg/l respectively;P=0.015]. Stratification of CHF patients according to tertiles of NT-proBNP revealed an increase in adiponectin with disease severity (P<0.0001). Exercise training reduced circulating adiponectin levels in CHF patients [10.7 (7.2-17.6) mg/l before training to 9.4 (5.9-14.8) mg/l after training;P=0.013], whereas no changes were observed in the sedentary CHF group [9.0 (7.0-13.5) mg/l before training and 10.1 (6.0-15.7) mg/l after a similar time interval]. A significant time x group interaction (P=0.008) was observed for the mean change in adiponectin between the trained and untrained CHF patients. Adiponectin concentrations were positively associated with NT-proBNP and HDL (high-density lipoprotein)-cholesterol and negatively correlated with BMI (body mass index), triacylglycerols and exercise capacity. In conclusion, circulating adiponectin concentrations are higher in CHF patients compared with healthy subjects and increase with disease severity.Exercise training for 4 months lowers circulating adiponectin levels.