PURPOSE OF REVIEW: As the population ages, the increase in chronic illnesses among patients with decreasing lung function will pose a major public health challenge. Determining which elderly patients are fit for surgery is an increasingly important skill. Anesthetic care of elderly patients requires an understanding of the effects that chronic diseases have on normal age-related changes in physiology and function. Postoperative respiratory complications are significantly increased in patients over 65 years of age, especially those with preexisting diseases. RECENT FINDINGS: Advanced age is associated with changes in the immunity of the pulmonary system. Dysregulation of pro-inflammatory mediators and antimicrobial defense systems contribute to a reduction in pulmonary function and its response to infections. Aging is also associated with a disruption of the function of alveolar macrophages, neutrophils, and natural killer cells. SUMMARY: Aging can increase the risk of postoperative complications because of a loss of physiologic reserve and airway defenses. These limitations may only become apparent after the stressors of surgery and anesthesia.