As an exhausted climbing expedition ascends a steep cliff, one climber in particular experiences severe difficulty breathing and quickly becomes the focus of this case study in which students are asked to assess the physiological changes that occur at high altitudes. The case is designed for upper division physiology students, most of who are interested in pursuing a career in the health sciences. Students are expected to have a basic knowledge of physiology of the respiratory system and some idea of how homeostatic mechanisms operate in a normal human.