The usefulness of endoscopic ultrasonography (EUS) in the evaluation of rectal varices (RV) was determined in 50 patients with portal hypertension (PH) and 25 PH-free controls. F1 and F2 varices and angiectasia were specific for the PH group as evaluated by endoscopy, but there was no difference between the PH and the control groups with respect to the frequency of blue vein. The detection rate of submucosal veins (SMV) with EUS was 88% for the PH group and 68% for the control group. The mean SMV diameter was significantly greater for the PH group than for the control group, and no 2-mm or larger SMV was detected in the control group. Serum albumin and cholinesterase levels were significantly higher for the RV(+) patients with SMV 2mm or more in diameter in the PH group than for the RV(–) patients. The spleen index was also significantly higher for the former group. The frequency of RV was significantly higher for advanced PH than for mild PH. RV(+) was detected in about 30% of endoscopically normal patients in the PH group. The results of this study indicate that EUS is useful in detecting RV and evaluating its pathological condition.