An understanding of how natural materials perform and how their assembly processes work is being applied to guide the design and performance of medical materials at the macro-, micro-, and nanoscale levels. This improved knowledge of natural and hierarchical structures along with advances in polymer science and nanotechnology have become the drivers for the synthesis of biomimetic materials. Highly sophisticated material performances can be achieved, eg, material self-assembly and self-healing, specific adhesion or repelling properties, biocompatibility in combination with biodegradability that broaden the specific uses in medicine. In this chapter, we describe key materials and assembly processes in nature and also cover their applications in three fields of bioengineering, namely, scaffolds for tissue engineering, biomedical adhesives, and smart drug delivery systems.