Plasma endothelin concentrations were evaluated in 53 chronic, congestive heart failure (CHF) patients with or without history of systemic hypertension, as well as in 9 with hypertension only and in 22 healthy control subjects. Plasma renin, aldosterone and atrial natriuretic peptide, as well as clinical and hemodynamic data were determined. In patients with CHF, big endothelin-1 was, independent of hypertension history, significantly greater than in hypertensive patients with normal cardiac function and in control subjects (both p < 0.0001). Patients with severe CHF had significantly greater big endothelin-1 values than did those with moderate CHF. During 12-month follow-up, 11 patients with CHF underwent heart transplantation, and 9 died; these patients had significantly greater big endothelin-1 concentrations than did the 33 clinically stable patients (p < 0.001). Big endothelin-1 and atrial natriuretic peptide correlated with right atrial pressure, pulmonary capillary wedge pressure, left ventricular ejection fraction, effort capacity and severity of CHF (New York Heart Association functional class).