Endocrinology is the study of the endocrine system and its hormones, which regulate various physiological functions in the body. The history of endocrinology spans from ancient times to the present day, and involves discoveries, experiments, and controversies in different countries and cultures. This chapter provides a brief overview of how endocrine disease were perceived and treated in ancient times, how the era of modern endocrinology began, discoveries that helped speedy progress of endocrinology and the major milestones and developments in the field, from the first descriptions of endocrine glands and hormones, to the analytical and synthetic methods of hormone measurement and replacement. At the end, the current and future challenges and opportunities in endocrine research and practice are discussed. This chapter also highlights the contributions of some of the pioneers and leaders in endocrinology, from the ancient times such as Hippocrates, Galen, and Avicenna and also from modern times such as Berthold, Brown-Séquard, Starling, and Banting, among others. The chapter aims to provide a comprehensive and historical perspective on the evolution and advancement of endocrinology as a scientific discipline and a clinical specialty.