The rational/structure-based design and/or combinatorial development of molecules capable of structurally and functionally mimicking the binding sites of proteins represents a promising strategy for the exploration and understanding of protein structure and function. The ultimate goal of using such molecules is the modulation of protein function through controlled interference with the underlying binding events. In addition to their basic significance, such proteinmimetics are also useful tools for a range of biomedical applications, in particular the inhibition of disease-associated protein-ligand interactions. Owing to their chemical and structural relation to proteins, as well as the relative simplicity of their chemical or recombinant synthesis, peptides have emerged as adequate molecules for the mimicry of protein binding sites, as well as the inhibition of protein-protein interactions.