Metal stents have become an important addition to therapeutic strategies available for incurable gastrointestinal malignancies. The responses of human tissues to the presence of metal stents are important for several reasons. The first is to understand the mechanism by which stents are anchored in the stenosis, as this will prevent migration of stents. The second is to develop new designs of stents that would be removable. The third reason is to prevent complications of stents, such as benign hypertrophy at the proximal and distal ends of the stent, and to understand the mechanism of serious complications, such as migration through the esophageal wall or aortoesophageal fistula. In this article, the authors discuss the state of the current knowledge in these three areas.