The efficacy of lung volume reduction surgery has been demonstrated by improvements in functional status, dyspnea, pulmonary function, alveolar gas exchange, and exercise tolerance. However, surgery has a significant morbidity, mortality, and cost. Surgical outcome is dependent on the clinical, anatomical, and physiological features of the patients and their emphysema. Therefore, the patient evaluation process and the preoperative optimization of medical therapy are crucial for success. Through understanding mechanisms for improvement have added insight to the selection process, patient selection needs further clarification.