Wireless capsule endoscopy (WCE) is a new technology that has been developed for investigation of the small bowel. Until recently, the small bowel was an organ which was difficult to explore, being largely blind to conventional endoscopic investigation. In routine practice only the last few centimetres of the ileum are accessible to retrograde exploration by ileocolonoscopy (IC). Investigation from the proximal side by push enteroscopy is a somewhat invasive procedure that usually does not allow the investigation of more than 60 cm of proximal jejunum. Small bowel WCE, therefore, represents a major advance; it is a safe, non-invasive procedure and many studies have established beyond doubt that it is cost-effective in a variety of clinical situations, including bleeding of obscure origin, detection of small bowel lesions in inflammatory bowel disease (IBD), non-steroidal anti-inflammatory drug enteropathies, and tumours. The context of using WCE to investigate the upper (oesophagus, stomach and duodenum) and lower (rectum and colon) gastro-intestinal (GI) segments is completely different. All these areas of the gut are easily accessible to conventional endoscopy, either by oesogastroduodenoscopy (OGD) or IC. These procedures are routinely performed by the majority of gastroenterologists; they allow biopsy sampling (which is not possible with WCE) and eventually therapeutic interventions such as polypectomy or mucosectomy. However, despite its merits, conventional endoscopy also has some limitations, which will be discussed specifically in this article in relation to the investigation of the upper and lower GI tract. Conventional endoscopy is also a relatively invasive procedure with high costs, especially when performed under sedation or general anaesthesia. Recently, novel developments in WCE technology have made possible the investigation of both the proximal and distal segments of the gut using specifically designed devices. The aim of this article is to review the published literature regarding these novel capsule endoscopic tools. Because …