Background: Endothelin is a newly discovered 21-aminoacid polypeptide that has been shown to produce marked vascoconstriction. Elevated plasma concentration of endothelin has been reported in patients with acute and chronic kidney failure, cardiogenic shack, hypertension, sepsis, acute myocardial infarction, subarachnoid hemorrhage and Raynaud`s phenomenon, and the reports suggest that endothelin plays a contrib- utnry role in the pathogenesis of those diseases. However, plasma levels of endothelin in patients with liver cirrhosis have rarely been reported. This study was conducted to investigate the clinical significance of plasma endothelin concentrations in patients with liver cirrhosis. Methods: Eleven patients with liver cirrhosis and ten healthy control subjects were included in this study. Plasma and random urine endothelin concentrations were measured by radioimmunoassay. Results: 1) The plasma endothelin concentration was significantly higher in patients with cirrhosis than in control subjects (15.5±5.1pg/ml vs. 3.9±2.4 pg/ml, mean±S. D, p<0.01). The urine endothelin concentration was also significantly higher in patients with cirrhosis than in control subjects (47.9±26.6 pg/ml vs. 15.3±9.2 pg/ ml, p<0. 05). 2) In patients with cirrhosis, the plasma endothelin concentration showed a significant negative correlation with creatinine clearance (r=0.76, p<0.01), and a significant positive correlation with fractional excretion of sodium (FENa) (r=0. 75, p<0. 01). Conclusion: From these results, elevated plasma endothelin may play a contributory role in kidney dysfunction in patients with cirrhosis.