Growth hormone (GH) or somatotropin (STH) is a protein hormone that stimulates growth and cell reproduction in humans and other animals. It is a 191-amino acid; single chain polypeptide hormone which is synthesised, stored, and secreted by the somatotroph cells within the lateral wings of the anterior pituitary gland. HGH promotes growth in children and plays an important role in adult metabolism. The body secretes the hormone, in decreasing amounts, throughout our lifetimes. The amount of hormone in the body can be measured by levels of IGF-1 (Insulin Growth Factor). Growth hormone has a profound effect on all the cells of the body, more than any other hormone because it is the cell generator. This book presents the latest research in the field.