This volume, the sixth in the series "The Prostaglandin System" assembles most of the lecture notes from the International School of Pharmacology on "Prostanoids and Drugs" that took place in Erice, Sicily, at the "Ettore Majorana Center for Scientific Culture" on Sept 5-15, 1989. The course, which was a NATO Advanced Study Institute, comprised detailed discussion of basic metabolic pathways of arachidonic acid as well as their location in the everyday practice of clinical medicine. The current status of our knowledge on drugs affecting prostanoid metabolic pathways, and/or their functinal effects, together with the use of prostanoids as drugs, has been reviewed in depth by distinguished experts. In certain instances a few chapters might overlap with others to present divergent viewpoints of authors, for a better assessment of the complexity of eicosanoid biology. It is likely that as our knowledge of prostanoids in different diseases increases, new diseases may also be targets for drugs related to these lipid mediators. We hope that this boo~will encourage basic scientists and clinicians to pursue additional biomedical investigations along these lines of inquiry. Moreover we would like to take this opportunity to express our gratitude to all the invited speakers not only for their important contributions before and during the course but also for their ability in creating an atmosphere in which all questions were legitimate and all lines of investigations were encouraged.