It is a basic interest of Man to look inside and understand the human body. This interest dates back to prehistoric times and is nowadays of diagnostic relevance in sick patients. It has led to the development of a variety of imaging methods for medical purposes within the 20th century. Among these, ultrasound is exceptionally appealing to both doctors and patients because of the wide variety of organs that can be investigated and because of its safety. The user, at any level, needs both theoretical knowledge and technical skills in its use. Various sites from the upper gastrointestinal tract to the anus are nowadays accessible by ultrasound. This review discusses the instruments for the sonographic evaluation of the gastrointestinal tract and gives an overview of their current applications.