Sonde-type enteroscopy has made it possible to potentially examine the entire depths of the small intestine. A relatively high diagnostic yield has been obtained by the sonde method in patients with obscure gastrointestinal bleeding. These features have made sonde enteroscopy a clinically accepted method. However, sonde-type enteroscopy has also some disadvantages making it less then a perfect endoscopy method. This article focuses on the technical aspects of sonde enteroscopy, but also summarizes the indications and the outcome of clinical studies.