For many years, peptides have been known to self-assemble to form nano- and micro-scale structures. Their nature of assembly and assembled morphology has since been investigated as this area of research has important implications for the development of both drug delivery and tissue regeneration. In this article, we explore the process of peptide self-assembly in vivo, and experiments that exploit the structures formed. Particular focus is directed towards diphenylalanine, the simplest self-assembling peptide, which generally forms tube-like structures on assembly. In addition, different peptides that may assemble into a range of other morphologies are highlighted and potential applications in regenerative medicine and drug delivery discussed.