Objective To explore the effects of thyroid hormone (TH) on cardiac function and peripheral lymphocyte β-adrenoceptors (β-Ars) of patients with chronic congestive heart failure (CHF). Methods Twenty-eight patients with class Ⅲ or Ⅳ advanced CHF due to dilated cardiomyopathy (DCM) or ischemic cardiomyopathy (ICM) were randomly divided into groups A and B. L-thyroxine (L-T50) was administered to group B. Exercise tolerance, chest X-rays, and echocardiographic parameters were obtained before and after one month of treatment, Ficoll-hypaque solution was used to separate peripheral lymphocytes, and 125I-pindolol radioligand binding was used to measure β-AR levels in peripheral lymphocytes. Results L-T50 therapy improved cardiac output [CO, (2.98±0.31)L/min vs (3.24±0.28) L/min, P<0.01], left ventricular ejection fraction (LVEF, 26.21%±3.21% vs 37.93%±9.01%, P<0.01), and decreased isovolumetric relaxation time (IVRT, 0.12±0.04 vs 0.10±0.02, P<0.01). Serum TH levels and the maximal number of β-AR binding sites (βmax ) in peripheral lymphocytes were lower in patients with CHF than in normal healthy people, but L-T50 administration induced a β-AR up-regulation on peripheral lymphocyte surfaces. L-T50 was well tolerated without episodes of ischemia or arrhythmia. There was no significant change in heart rate or metabolic rate.Conclusion TH administration improves cardiac function and β-AR expression in peripheral lymphocytes of patients with CHF.