A new therapeutic trial aimed at assisting tissue regeneration at a body defect in size too large for self-repair has recently begun. The objective is to substitute the biological functions of damaged and injured organs by taking advantage of cells. For successful tissue regeneration, it is absolutely indispensable not only to have cells of high proliferation and differentiation potential, but also to create an environment suitable for inducing regeneration. Such creation can be artificially achieved only by providing various biomaterials to promote cell proliferation and differentiation, such as cell scaffold and growth factors. Growth factors are often required to promote tissue regeneration because they can induce angiogenesis, which promotes a sufficient supply of oxygen and nutrients to effectively maintain the biological functions of cells transplanted for organ substitution. However, because of their poor in vivo stability, the biological effects of growth factors cannot always be expected unless these drug delivery systems (DDSs) are contrived. In this chapter, several research approaches to tissue regeneration are reviewed to emphasize the significance of biomaterials and DDS technologies in regenerative medicine.