Endoscopic examination of the small bowel, until recently, has been elusive because of the bowel’s relative inaccessibility. Standard endoscopic examinations evaluate only short segments of the proximal and distal small bowel. Until recently, intraoperative enteroscopy was considered the gold standard, providing the highest diagnostic and therapeutic yield in patients with bleeding from the small bowel. This was, however, associated with a substantial risk for complications and mortality (Desa et al. 1991). The double-balloon enteroscope (DBE) is a instrument that was first described by Yamamoto in 2001 (Yamamoto et al. 2001), and its system was first developed by the Fujinon Corporation in 2003 (Yamamoto et al. 2003). It has a high success rate of intubation into the deep small intestine (Kaffes et al. 2006; Yamamoto et al. 2004) and allows endoscopic evaluation of the small bowel with interventional capabilities. Its use has subsequently grown worldwide. The first international workshop on DBE was held in Japan in August 2006 (Sugano and Marcon 2007). This chapter aims to describe the DBE procedure and its progress in recent years.