We report the case of a young man presenting clinical features of portal hypertension of unknown origin. The ultrasonographic examination showed suprahepatic blockage signs leading to the diagnosis of Budd-Chiari syndrome caused by incomplete diaphragm of the inferior vena cava. The color Doppler examination suggested caval obstruction, showing an abrupt shift from a laminar to a bosterous flux. Secondly cavograms and surgery later confirmed the diagnosis.