The Peptides: Analysis, Synthesis, Biology, Volume 6: Opioid Peptides: Biology, Chemistry, and Genetics presents a biological topic of peptide research. This book is divided into nine chapters. Chapter 1 reviews the opioid peptide precursors and their genes. The proenkephalin and products of its processing are discussed in Chapter 2. In Chapter 3, the role of pro-opiomelanocortin (POMC) as a protein at the interface of the endocrine and nervous systems is examined. Chapter 4 provides a comprehensive account of the biology and chemistry of the dynorphin peptides. The opioid receptors are described in Chapter 5. Chapter 6 evaluates the structure-activity relationships of ?-endorphin, while Chapter 7 considers the conformational analysis of enkephalins and conformation-activity relationships. The structure-activity relationships among enkephalin peptides are elaborated in Chapter 8. The last chapter is devoted to the clinical significance of opioid peptides in humans. This publication is a good reference for biologists, specialists, and researchers concerned with peptides and proteins.