AIM To investigate the expression of endothelial NO synthase (eNOS), inducible NO synthase (iNOS)protein and eNOS mRNA gene in the splanchnic organs of liver cirrhosis and portal hypertensive rats.METHODS In control and CCl4-induced liver cirrhotic rats, the expression of eNOS and iNOS proteins wasdetected by immunohistochemical method, and eNOS mRNA was detected by in situ hybridization.RESULTS The expression of eNOS protein and eNOS mRNA increased in most organs of the cirrhotic rats,including bronchial and alveolar epithelial cells, renal tubular epithelial cells and mesenchyma, endothelialand adventitial cells of aorta and superior mesenteric artery, whereas no significant increase of iNOS proteinwas found. In the hepatic tissue, NOS protein and eNOS mRNA were present in mesenchymal cells and vesseladventitial cells, no difference was observed in the expression between control and cirrhotic rats.CONCLUSION The expression of NOS varied in region. In splanchnic organs and vasculars there was anincreased expression of eNOS which induced aplanchnic vasodilation and increased the inflow of portal vein,while in the liver tissue and blood vessel showed no increased expression, which may be associated withincreased intrahepatic vascular resistance.