Clinical and portal hemodynamic features in 28 cirrhotic subjects with a large spontaneous spleno- and/or gastrorenal shunt were studied in comparison with 30 control cirrhotic cases without such collaterals. Forty-six percent of the former had chronic hepatic encephalopathy, but none of the latter was encephalopathic. These patients with large renal shunts were divided into those with and those without encephalopathy. Large esophageal varices were significantly less common in patients with a large shunt and encephalopathy compared with those who had a large shunt but no encephalopathy, and the control. But there was no significant difference of past variceal bleeding among these three groups. In all those with encephalopathy, part of superior mesenteric venous blood was shunting through these collaterals into the left renal vein or inferior vena cava, but the same was not demonstrable in patients with a large shunt and no encephalopathy and control cirrhotics. In the chronic encephalopathic, portal venous flow was estimated to be less than one-half of that in control cirrhotics, and the portion of superior mesenteric venous blood that was flowing hepatofugally through a large shunt into the left renal vein seemed about the same or greater than the portal venous flow. Thus, a large spontaneous spleno- and/or gastrorenal shunt might prevent development of large esophageal varices but not variceal hemorrhage and it increased a risk of chronic hepatic encephalopathy.