Patients suspected of having portal hypertension (either by clinical history, physical examination, or previous diagnosis) should undergo ultrasonography and upper gastrointestinal endoscopy. Ultrasonography, preferably using the duplex technique, can disclose the patency of the portal venous system, the presence of signs of portal hypertension (splenomegaly, portocollateral vessels, repermeabilization of the umbilical vein, and so forth) and provide additional information about liver, biliary, or pancreatic diseases that may be the cause of portal hypertension. Endoscopy can assess the presence and size of gastroesophageal varices, the appearance of the variceal wall, and the presence and severity of portal hypertensive gastropathy. Patients showing a patent portal vein should have hepatic vein catheterization to evaluate the presence of presinusoidal, sinusoidal, or postsinusoidal portal hypertension. Patients in whom presinusoidal portal hypertension is suspected (those having esophageal varices with an HVPG below 10 mm Hg) should have liver biopsy and percutaneous transhepatic measurement of portal pressure. In sinusoidal portal hypertension, the results of endoscopy and HVPG measurement are decisive for the therapeutic management of the patients. The authors' results indicate that, before starting prophylactic therapy with beta-blockers, all patients should undergo at least an hepatic vein catheterization to assess HVPG; it would be preferable to have a variceal pressure measurement also. These measurements must be repeated 3 to 4 weeks after the final dose of therapy has been reached to assess the risk of variceal bleeding or rebleeding.