RATIONALE: Although chronic obstructive pulmonary disease is the first indication for lung transplantation, the benefit of the procedure in terms of survival remains debated. OBJECTIVES: To estimate the determinants of the survival benefit of lung transplantation in patients with chronic obstructive pulmonary disease. METHODS: Using information from the United Network for Organ Sharing database on 8,182 patients, we developed an approach based on numerical simulations to estimate the survival effect of lung transplantation. MEASUREMENTS AND MAIN RESULTS: The main outcome measure was the difference between median survival with transplantation and that without transplantation measured from time of transplant list registration. Survival benefit was greater with double than with single lung transplantation (mean difference, 307 d [95% confidence interval, 217-523]). With double lung transplantation, 44.6% of patients would gain 1 year or more, 29.4% would gain or lose less than 1 year, and 26% would lose 1 year or more. Major determinants of the survival effect of transplantation were systolic pulmonary artery pressure, FEV(1), body mass index, exercise capacity, functional status, and the need for continuous mechanical ventilation or oxygen. For instance, 79% of patients with an FEV(1) less than 16% of the predicted value would gain 1 year or more with double lung transplantation as compared with only 11% of patients with an FEV(1) of more than 25%. CONCLUSIONS: We identified several factors associated with the survival benefit of lung transplantation. External validation of our models is required before translating these results into clinical practice.