Areas of application for endosonography can be roughly divided into three categories: standard diagnostic examination; operative diagnostic examination (fine-needle aspiration); and operative therapeutic procedures. Nevertheless, endoscopic ultrasonography remains a single technique, in which the physician can not only raise a suspicion of a particular disease, but can also obtain cytological confirmation when needed and carry out a therapeutic procedure when indicated. Widely accepted indications for endosonography are the staging of esophageal and rectal cancer, and the visualization of submucosal lesions and gastric wall diseases; other indications, such as imaging of the pancreas and biliary tree, are still being discussed.