Several investigators have examined the use of nanostructured forms of diamond for cardiovascular, dental, and orthopaedic applications. Diamond exhibits unusual mechanical, biological, and chemical properties that make it an ideal interface between medical devices and the biological environment. For example, ultrananocrystalline diamond and nanocrystalline diamond films have been grown using chemical vapor deposition on ceramics and metals. In this talk, in vitro studies of interactions between nanostructured forms of diamond and cells will be considered. In addition, recent developments involving the use of diamond in medical devices will be described.