This volume of Pharmacochemistry Library comprises the text of invited lectures presented at the 11th Noordwijkerhout-Camerino Symposium Trends in Drug Research, held in Noordwijkerhout, The Netherlands, from 11-15 May 1997. In the programme attention has been given to the generation of new biological target systems and the generation of new lead molecules, with presentations on e.g. combinatorial chemistry, compound libraries, database search, high throughput screening and molecular biology. Other topics discussed were the perspectives for new medicines for the gastro-intestinal tract, the major developments in the search for effective anti-HIV drugs and new aspects in synthetic approaches. In a special session three topics which currently draw much attention were discussed: How to deal with the major problem of resistance against antimirobial agents? Can the apoptosis mechanism be used as a drug target? Is the newly observed phenomenon of inverse agonism a general principle and has it consequences for drug development (and use?)