This is a request for partial support for a symposium on extension of oxygen tolerance. Support is requested specifically to defray airfares associated with travel of invited participants in the symposium. The impetus for the symposium is the upcoming retirement of Dr. Christian J. Lambertsen and the 20th Anniversary of the Institute which he founded. The purpose of the symposium is to bring together experts in the field of oxygen toxicity with special reference to methods to extend oxygen tolerance in man. Considerable research in the past 20 years has identified mechanisms of oxygen toxicity and its pathophysiology. Animal studies from various labs have provided data related to oxygen tolerance in animals that are applicable to man. Much of this work has revolved around the free-radical theory of 02 toxicity and the role of anti-oxidant enzymes. There have been frequent conferences and symposia related to these free-radical mechanisms and to the pathophysiology of oxygen poisoning. However, there has been no meeting specifically oriented to the application of this research to human oxygen tolerance. It is the purpose of this conference to bring together researchers involved in these new developments in order to provide a forum for the consideration of human oxygen tolerance and possible methods for modifying tolerance.