The utility of implanted sensors, drug-delivery systems, immunoisolation devices, engineered cells, and engineered tissues can be limited by inadequate transport to and from the circulation. As the primary function of the microvasculature is to facilitate transport between the circulation and the surrounding tissue, interactionsbetween biomaterials and the microvasculature have been explored to understand the mechanisms controlling transport to implanted objects and ultimately improve it. This review surveys work on biomaterial-microvasculature interactions with a focus on the use of biomaterials to regulate the structure and function of the microvasculature. Several applications in which biomaterial-microvasculature interactions play a crucial role are briefly presented. These applications provide motivation and framework for a more in-depth discussion of general principles that appear to govern biomaterial-microvasculature interactions (i.e., the microarchitecture and physio-chemical properties of a biomaterial as well as the local biochemical environment).