The ribosomally-translated protein molecules found in Nature are homochiral. They made up of L-amino acids and the achiral amino acid glycine. Modern chemical ligation methods enable the total synthesis of unnatural protein molecules made up entirely of D-amino acids and glycine.[1-3] These D-proteins have a folded structure that is the mirror image of their counterparts found in Nature. The prototypical synthesis of a mirror image enzyme molecule demonstrated reciprocal chiral substrate specificity.[4,5] Mirror image protein molecules have a variety of uses.[6] Crystallization of racemic protein mixtures consisting of D-protein and L-protein enantiomers has greatly facilitated the solution of novel protein X-ray structures.[7,8] Most importantly, D-proteins enable ‘mirror image drug discovery’, to identify unique therapeutic leads from chiral compound libraries.[9] D-Protein molecules themselves are good candidates for use as human therapeutics: they are resistant to proteolytic digestion, are longer-lived in vivo, and are non-immunogenic.[10] To illustrate the properties and applications of mirror image protein molecules, I will describe the application of total synthesis to the creation of uniquely chemical D-protein antagonists of an important therapeutic target.[11]