Although intravascular stents have received widespread application, significant limitations remain. In stent restenosis, the most pervasive problem affecting stents, is related in part to technical aspects of the device. Design features of the stent that influence outcome have been identified and optimized for improved performance. The influence of stent materials on critical aspects of healing, such as thrombotic, inflammatory, and hyperplastic responses, are less well understood. For this reason, significant progress in this area is lacking. Current stents have significant contamination with industrial impurities on the surface and in the bulk. This fact adds to the difficulties in interpreting the biologic reaction of the host to the device. Better understanding of the basic biologic interactions is the path to significant improvement.