Thirty adult patients without portal hypertension, and one with severe portal hypertension, underwent cannulation of the umbilical vein without ill effects. The portal vein was successfully entered in 29 cases. Perforation of the umbilical vein occurred in one case, and the catheter was apparently inserted into the ligamentum venosus in one case. In 12 of 14 portograms attempted there was good or excellent visualization of the portal venous system, and the films confirmed the end-on relationship of the umbilical vein with the left portal vein in the umbilical fissure of the liver, most of the vessels visualized being intrahepatic. Portal pressures averaged 17.3 cm of saline in 11 noncirrhotic patients.