Mehul Dattani, Professor of Paediatric Endocrinology at Great Ormond Street hospital, has made seminal contributions to our understanding of the molecular and genetic basis of hypothalamic-pituitary development and is widely acknowledged as an international leader in Paediatric Endocrinology. Over the last 25 years, he has led or collaborated on the discovery of 12 rare inherited endocrine disorders. Cumulatively, his discoveries have informed diagnostic genetic testing for a spectrum of disorders, which is now available around the world. He has led the development of clinical services at Great Ormond Street Hospital and has trained many excellent academic Paediatricians who come to work with him from around the world.