The dramatic expansion in genomic information has motivated the development of new approaches to characterize gene expression and function. A critical issue for both basic and clinical endocrinologists is the physiological role of genes involved in regulating endocrine functions. Transgenic technologies allow the translation of genotypic information into specific phenotypes by using gene overexpression or loss of specific gene functions. This book has been designed to reflect a multidisciplinary approach to transgenics in endocrinology, encompassing contributions from internationally recognized experts in many aspects of endocrine physiology. These range from the basic technologies underpinning the generation of transgenic rats and mice, to knock-out mice and also transgenics using viral vectors for gene delivery. The authors have aimed to exemplify the use of transgenic technologies and models for the study of a wide range of endocrine topics, including, reproductive functions, the stress axis, control of lactation, water and electrolyte balance, appetite control and pituitary tumour therapy.