A technique was developed for identifying peptides with high affinity for a given antibody. By testing a monoclonal antibody directed against a discontinuous antigenic determinant on foot-and-mouth disease virus, peptides mimicking the determinant were identified even though the tertiary structure of the proteins comprising the virus capsid is unknown. The allowable variations in spacing and stereochemistry of the peptides shown to mimic this epitope suggest protein folding in which amino acid residues from three regions, distant from one another in the primary sequence, are brought into close proximity at this epitope. The technique has potential for identification of peptides which will bind with high affinity to receptors other than antibody molecules.