Along with endosonographic fine needle aspiration, transoesophageal ultrasonography is now well established for staging gastrointestinal tumors. It is especially well suited to assessing mediastinal structures due to its transoesophageal approach and its high local definition. The mediastinum can be viewed all the way from the tracheal bifurcation to the diaphragm. This technique is already in regular use for pulmonary problems and especially for staging pulmonary carcinomas.