The Seventh International Hypoxia Symposium was held in Lake Louise, Canada, February 1991. The Symposium explored adaptations to hypoxia in animals and man including an important section on comparative physiology. The interface between state-of-the-art basic science and clinical aspects of high altitude was discussed. Papers that are collected in this volume describe current concepts of lack of oxygen in birds, insects, mammals and in astronauts, mountaineers and casual tourists. These proceedings are a unique blend of basic molecular biology, comparative physiology and the practical application of these physiological concepts to the clinical and mountain worlds. This text is a major addition to the understanding of hypoxia and its management.