Endothelin (ET)-1 is a potent vasoconstrictor with growth promoting and mitogenic properties associated with various cardiovascular diseases (CVD) and has been found to be an important protagonist in congestive heart failure (CHF). The introduction of ET-1 receptor antagonists into the arena of clinical research has amplified our understanding of the ET system: the first human trials with acute and chronic inhibition of the ET system have shown promising results and confirm the findings from experimental models. The availability of oral compounds such as bosentan has raised the hope that these novel drugs might become a new therapeutic class of agents for the treatment of CVD and, in particular, of CHF. The question, however, remains whether the beneficial effects observed so far in patients with CHF go beyond simple hemodynamic improvements and whether these compounds improve long-term survival in these patients.