Peptides that mimic protein epitopes are interesting drug candidates. However, the design of effective peptidic drugs is difficult for several reasons, such as the fast degradation of peptides, their high flexibility, and thus high entropy loss on binding to the target. We therefore propose an in silico method for the automated design of peptides that are optimal with respect to several objectives. We present a Pareto-based multiobjective evolutionary algorithm for in silico peptide design. Using a simple molecular model, we apply the method to the design of peptides that (a) mimic antibody epitopes of the proteins thrombin and blood coagulation factor VIII, respectively, that (b) are short, and (c) are conformationally stable. 2, D-53175 Bonn, Germany.