The Eleventh American Peptide Symposium was held on the San Diego campus of the University of California in picturesque La Jolla on July 9-14, 1989. More than 1100 participants from around the world came to attend a scientific program comprised of an assortment of oral presentations, posters and exhibits. Most rewarding to us was the regular attendance at all the scientific sessions by our registered guests despite the beautiful scenery offered by La Jolla and San Diego county. Indeed for all of us, the purpose of the biennial American Peptide Symposium is to try to keep up with a fast evolving and fascinating field. The goal of the proceedings of these meetings is to provide the scientific community unable to attend some or all of the Eleventh American Peptide Symposium with a synopsis of current results in peptide research. Of 65 oral presentations and approximately 390 poster displays, the Program Committee selected 393 articles for publication. A few manuscripts by distinguished invited speakers were unfortunately not received in time to appear in these proceedings. All manuscripts herein were selected on the basis of their originality at the time of presentation and their significance in the development of peptide-related research. As in the past, this Eleventh meeting brought together scientists with a wide range of expertise, which was harnessed to address and solve basic as well as applied scientific problems in broad areas.