n Human Growth Hormone: Research and Clinical Practice, we have been fortunate to be able to convince many of the leaders in the field to write about the recent developments in the understanding of basic and clinical research in the field of human growth hormone. During the last few years, there have been major advances in this field, one that has been dramatically enhanced by the discovery of the growth hormone-releasing peptide. This spawned much novel research, and ultimately led to the cloning of the receptor for the growth hormone secretagogues. The understanding of the molecular biology, structure, and function of growth hormone and the growth hormone receptor complex has also set a new standard in the understanding of the structural biology of cell signaling