Endoscopic ultrasonography makes it possible to measure and examine the wall of the upper gastrointestinal tract. It complements endoscopic visualization of the surface with analysis of the wall layers. Endoscopic ultrasound imaging reveals five different layers. Preliminary results indicate that benign gastric tumours can be distinguished from infiltrating gastric carcinoma. The extent and adjoining reaction of a gastric ulcer can also be visualized. Endoscopic ultrasonography of the stomach is a method of investigation that can be further developed and already shows considerable diagnostic potential.