The purpose of the present volume is to illustrate the modern biological concept of basic endocrinology in one single book. It first describes general issues such as maturation of secretory granules in the cells, the roles of the chaperonic granins, and cell-specific prohormone processing. Subsequently, the specific part of the book illustrates the new endocrine biology, using as examples a broad variety of individual peptide systems: ACTH, Neurotensin and Neuromedines, Natriuretic Peptides, Glucagon and Glucagon-like peptides, Somatostatin, Ghrelin, Gastrin and VIP (Vasoactive Intestinal Polypeptide).