Although many factors have been shown to relate to survival in patients with COPD, the patient's age and baseline postbronchodilator FEV1 are the best predictors of mortality. The presence of mild obstructive airway disease is not indicative of a progressive downhill course and shortened survival. Mortality in patients with a baseline postbronchodilator FEV1 greater than or equal to 50% of predicted was only slightly greater than that of a group of healthy smokers. Investigators attempting to compare survival in patients with COPD should attempt to exclude patients with asthma or asthmatic bronchitis, because these individuals have a much better prognosis than those with typical COPD (emphysema and chronic bronchitis). Patients should be matched closely for age and severity of impairment, because younger individuals and those with milder impairment are likely to live longer. Other factors besides age and baseline FEV1 have been shown to affect survival. Patients who stop smoking are likely to survive longer than those who continue to smoke. The presence of malnutrition has clearly been shown to worsen survival. Further studies will be necessary to determine if corticosteroid therapy can slow down progression of disease in patients with typical COPD. Oxygen therapy improves survival in COPD patients with significant hypoxemia, many of whom also have CO2 retention, polycythemia, and cor pulmonale. There are now multiple studies in the literature suggesting that the type of comprehensive respiratory care provided by pulmonary rehabilitation programs can not only improve the quality of life but also survival in patients with chronic obstructive pulmonary disease.