The tradition of setting new trends in medicinal chemistry continued at the 13th Symposium where topics included chemical and biological diversity, new paradigms in drug action, and new insights in receptor mechanisms. Other topics of great interest discussed, and included in these proceedings, are the discoveries in green chemistry, the interface between organic synthesis and biosynthesis, the growing problem of resistant micro-organisms and the possibilities to identify new, and better, antibiotics. And finally, in recent developments, the discovery of small molecules with insulin sensitizing properties.