Objectives To evaluate the changes of the plasma endothelin level in patients with dilated cardiomyopathy, and to investigate the relationship between the plasma endothelin level and the severity of heart failure, heart size, left ventricular function and with or not with pulmonary arterial hypertension; the changes of the plasma endothelin level before and after treatment. Methods The plasma endothelin level of 30 patients with DCM, 30 healthy control subjects, and their LVEF, PAP, heart size, plasma endothelin level before and after treatment were determined.Results The plasma endothelin level in DCM group was significantly higher than that in control group (135.93 ± 70. 65pg/mL) vs(43.65 ± 12.07pg/mL),P＜0.05; there was a correlation between ET level and heart size ( r = 0. 4580, P = 0. 0109); there was a significant negative correlation between LVEF of DCM and ET level(r = -0. 6922,P =0. 0021 ) ;and it was a significant positive correlation between ET level and pulmonary arterial hypertension (r = 0. 8974, P ＜0. 0005). After treatment, the ET level decreased significantly than before in DCM group (129.15 ±43.93pg/mL) vs (63.12 ± 22.20pg/mL), P ＜0.05. Conclusions Plasma ET level may be a new parameter of evaluating severity of heart failure, efficacy of therapy and prognosis.