Background: Colorectal varices and congestive rectopathy or colopathy have been erratically reported in patients with portal hypertension. The clinical importance of these entities has not been described. We assessed the changes in the venous system of the rectum by endoscopy and rectal endosonography (EUS). We also assessed the role of factors such as etiology of portal hypertension, grade of esophageal varices, sclerotherapy, and liver disease severity on the occurrence of these vascular changes. Methods: We studied changes in the venous system of the rectum using endoscopy and EUS in 60 patients with portal hypertension (cirrhotic 41, noncirrhotic 19). Ten patients with irritable bowel syndrome and 6 patients with hemorrhoids served as controls. Rectal varices were classified as tortuous, nodular, and tumorous. Corresponding appearances on rectal EUS were classified as single or discrete multiple, multiple, and innumerable submucosal veins, respectively. Evidence of congestive rectopathy was also recorded. Results: Prevalence of rectal varices was 43.3% on endoscopy (73% tortuous, 19% nodular, and 8% tumorous) and 75% on EUS (p < 0.0005). The latter showed corresponding appearances of submucosal veins in 25 of 26 patients and detected submucosal veins not identified at endoscopy in 19 other patients. Congestive rectopathy was found in 38.3% of patients. Multiple small dilated vessels in the submucosa were seen in 23.3% patients on rectal EUS. The development of these vascular changes was significantly influenced by sclerotherapy, but not by higher grade of esophageal varices, the etiology of portal hypertension, or severity of liver disease. Conclusions: Changes in the rectal venous system are common, with rectal EUS being superior to endoscopy in detecting early, as well as florid, changes. (Gastrointest Endosc 1999;49:218-27)