There are multiple changes that occur to the respiratory system with aging. In the absence of significant disease, the majority of such changes do not result in any significant impact on lung health. However, such changes do affect physiologic testing and susceptibility to environmental insults which are essential to understand in the context of the patient being considered for thoracic surgery. Normal physiologic changes to the chest wall and supporting structures, airway and lung compliance, alveolar surface area, and pulmonary vasculature all result in a reduction in lung function and may also be associated with reduced exercise capacity. Gas transfer in elderly patients is less efficient than those who are younger, but this seldom is clinically significant. Elderly patients are also more susceptible to infection and a higher mortality associated with such infections due to alterations in host defense mechanisms and the frequency of comorbid conditions.