The evolution in our understanding of opioid receptors and their subtypes is in- mately linked to the development of new pharmacological treatments for diseases/ disorders as diverse as addiction, self-injurious behavior, pain, cancer, infl- mation, eating disorders, traumatic injury, pruritis, and movement disorders. These potential treatments involve both novel chemical entities and classic opioid antagonists with improved drug delivery systems. The contributions contained in Opioid Receptors and Antagonists: From Bench to Clinic represent the efforts from some of the leading international scientists and clinicians making use of the l- est information emerging from the study of the opioid receptor system. Given the number of researchers currently active in this and related fields of study, it would be inappropriate to suggest that the entire range of activities is fully reflected in this single volume. Instead, a variety of experimental and clinical approaches involving the fields of neuroscience, molecular biology, biochemistry, anatomy, pharmacology, psychology, and psychiatry have been chosen to illustrate rapidly developing experimental and therapeutic areas.