Since the introduction of double-balloon enteroscopy (DBE), the small intestine has come into easy reach for endoscopy. By the 'push and pull' technique, the endoscope can be introduced far into the small intestine. Diagnostic endoscopy can be combined with endoscopic treatment in the small intestine, for example in patients with intestinal bleeding (angiodysplasia), polyps, tumours, or stenosis of the small intestine. DBE is especially important for patients with gastrointestinal blood loss that cannot be explained by the results of gastroscopy and colonoscopy. The added value of DBE in patients with other possible diseases of the small intestine, such as refractory coeliac disease or Crohn's disease, seems certain and is currently under investigation. In patients with Crohn's disease, endoscopic dilation of strictures may eliminate the need for surgical intervention. DBE can be performed on an outpatient basis. The complication rate of diagnostic DBE seems low, but in therapeutic sessions the complication rate is higher than for therapeutic colonoscopy.