HE history of high-altitude physiology and medicine is such a rich and T colorful topic that it is perhaps surprising that no one has undertaken a comprehensive account before. There are so many interesting ramifications, from the early balloonists to the various high-altitude expeditions, culminating in the great saga of climbing Mt. Everest without supplementary oxygen. Underpinning this variety is the basic biological challenge of hypoxia and the ways organisms adapt to it, a subject that is of key importance in medicine and many other life sciences, encountered as it is by organisms throughout the animal kingdom. I hope that this book will be of interest to a wide range of people, from biologists and physiologists to pulmonologists and others who manage patients with hypoxemia. The topic should also appeal to those who love the mountains including trekkers, skiers, climbers, and mountaineers. The book begins with a short introductory chapter to set the scene for the non-scientist. It then follows a general chronological sequence beginning with the Greeks and ending with contemporary events. In some places, however some compromises have been made to group together areas of related interest. For example, in Chapter 4 the controversy about oxygen secretion is traced from the 1870s to the 1930s and includes the Anglo-American Pikes Peak Ex pedition of 1911 and the International High-Altitude Expedition to Cerro de Pasco, Peru during 1921-1922. It makes sense to consider these events together.