The 'Yearbook of Pediatric Endocrinology 2006' brings you abstracts of articles that reported the year's breakthrough developments in the basic sciences and evidence-based new knowledge in clinical research and clinical practice that are relevant to the field. Twelve Associate Editors and their co-authors have done an immense job poring over the top journals to discover this year's advances, and provide their chapters in a timely fashion. These cover the identification of new genes involved in diseases, new hormones, concepts revised or recentered, important observations for clinical practice, large-scale clinical trials, new mechanisms, new paradigms, important review articles, new fears and new hopes. This is the third volume of the 'Yearbook of Pediatric Endocrinology'. To acknowledge the European Society for Paediatric Endocrinology (ESPE) endorsement of the Yearbook, the publication of the Yearbook is linked to ESPE's annual meetings, and hence, this volume is published only nine months after the previous one, covering the medical and scientific literature from June 2005 through April 2006. The 'Yearbook of Pediatric Endocrinology 2006' will help busy clinicians and scientists, pediatric endocrinologists, and also pediatricians and endocrinologists keep informed on new advances in their field.