Endoscopic studies were performed to determine whether changes occurred in the duodenum related to portal hypertension in patients with liver cirrhosis. The total of 271 patients studied were subdivided into three groups: 83 patients with liver cirrhosis and portal hypertension, 53 with liver cirrhosis but no portal hypertension, and 135 controls. In the duodenum of cirrhotic patients with portal hypertension several changes were observed on endoscopy that were also present in the other two groups. Atrophy and vascular malformations, however, were present only in the duodenum of cirrhotic patients with portal hypertension, although in only a few patients and with statistical significance only for vascular malformations (p less than 0.01, phi = 0.21). Eleven percent of the patients had more than one endoscopic finding, but the associations of findings were without statistical significance. No statistically significant correlation was observed between the clinical severity of cirrhosis or the severity of esophageal varices and the endoscopic findings. Finally, there was no statistically significant difference between the histological findings of duodenitis in the three groups of patients.