Background/Aims: This study was designed to find out the effects of nitric oxide (NO) on the splanchnic and extrasplanchnic vascular hemodynamics of patients with liver cirrhosis using Doppler ultrasonography. Methods: For 43 controls and 67 patients with cirrhosis (39 in Child A and B, 28 in Child C), blood flow and resistive index (RI), pulsatility index (PI) of the superior mesenteric artery (SMA), and cardiac output and systemic vascular resistance index were measured with Doppler ultrasonography. The serum NO concentration of all subjects was measured using Griess reaction. Results: In cirrhosis group, the flow of SMA blood was increased and the concentration of NO was significantly higher than in controls. The increase in SMA blood flow paralleled the degree of liver dysfunction. SMA RI and PI were significantly lower in cirrhosis group than in controls, and the decrease in SMA RI and PI paralleled the degree of liver dysfunction. NO had a significantly negative correlation with SMA RI and PI, but not with systemic vascular resistance index. Conclusions: Doppler ultrasonography may be a useful method for evaluating hemodynamics in patients with liver cirrhosis. Moreover, an increase in splanchnic blood flow maintaining portal hypertension is associated with a decrease in splanchnic vascular resistance which might be mediated by NO. (Kor J Gastroenterol 2000;35:466 - 474)