The prevalence of spontaneous reversal of flow in the portal venous system was non invasively evaluated by Doppler ultrasound in 228 patients with liver cirrhosis and portal hypertension. Reversed flow was detected in the portal vein in 7 patients (3.1%), in the splenic vein in 7 patients (3.1%), and in the superior mesenteric vein in 5 patients (2.1%), with an overall prevalence of 8.3% (19/228). This prevalence did not differ in relation to the etiology of liver cirrhosis, whereas hepatofugal flow was found in more patients classified as Child's C (15.4%) and B (12.5%) than those classified as Child's A (2.7%) (P less than 0.02) and was associated with a higher frequency of hepatic encephalopathy (21% vs. 7.2%; P less than 0.05). Endoscopic evaluation of esophageal varices did not reveal any correlation between the presence and size of varices and hepatofugal flow, whereas red signs were detected more frequently in patients with this hemodynamic pattern (42.1% vs. 24.4%; NS). The rate of previous variceal bleeding was not significantly different in patients with and without hepatofugal flow (30.8% vs. 24.4%; NS). Conversely, the prospective evaluation of 15 patients with hepatofugal flow and 29 matched patients with hepatopetal flow, derived from the group of 228 patients, followed up for a period of 12-18 months, showed that variceal bleeding occurred in 9 of 29 patients with hepatopetal flow and in none of the 15 patients with hepatofugal flow (P less than 0.02). However, no statistical difference was found in the survival rates. This study indicates that the actual prevalence of reversed flow in the portal, splenic, and superior mesenteric veins in a nonselected cirrhotic population is 8.3%. From a clinical point of view, the data suggest that this finding might be considered an important prognostic factor because, while occurring in cirrhotic patients with more severe functional impairment, it might play a protective role against the risk of bleeding.