Cystic fibrosis is a common indication for lung transplantation. Under the current organ allocation system, donor lungs are distributed to patients based solely on their accrued waiting time, and the death rate on the waiting list has been high. Physiologic parameters have been used to guide the referral, but risk factors for death while awaiting transplantation have not been well defined. This study aimed to identify factors at the time of evaluation that were associated with death on the waiting list. A consecutive cohort of 146 patients with cystic fibrosis who were listed for lung transplantation was retrospectively reviewed. Characteristics of patients who died awaiting transplantation were compared with those of patients who survived until transplantation or the end of the study. Thirty-seven patients died while waiting, 76 underwent transplantation, and 33 were alive and still waiting. Actuarial survival rates for the entire cohort were 81% at 1 yr, 67% at 2 yr, and 59% at 3 yr. Although a multivariate Cox proportional hazards model (chi(2) = 29.6; p < 0.001) identified shorter six-minute walk distance (50 m increments; RR, 0.69; 95% CI, 0.57 to 0.84), higher systolic pulmonary artery pressure (5 mm Hg increments; RR, 1.41; 95% CI, 1.11 to 1.80), and diabetes mellitus (RR, 1.57; 95% CI, 1.06 to 2.32) as significant risk factors for death on the waiting list, these factors and other features overlapped considerably between the group of patients who died waiting and the group who lived until transplantation or the end of the study. The transplant evaluation selects a rather homogeneous cohort of patients for the waiting list. Unless outcome on the waiting list can be reliably predicted, establishing criteria to allocate donor lungs according to medical urgency may not be feasible.