BACKGROUND: Pulmonary function tests predict respiratory complications after lobectomy. We evaluated the impact of pulmonary function measurements on long-term survival after lobectomy for stage I non-small cell lung cancer. METHODS: The relationship between percent predicted forced expiratory volume in 1 second (FEV1) and percent predicted diffusing capacity of the lung for carbon monoxide (Dlco) and overall survival for patients who underwent lobectomy without induction therapy for stage I (T1-2N0M0) non-small cell lung cancer from 1996 to 2012 was evaluated using the Kaplan-Meier approach and a multivariable Cox proportional hazard model. RESULTS: During the study period, 972 patients (mean Dlco 76 ± 21, mean FEV1 73 ± 21) met inclusion criteria. Perioperative mortality was 2.6% (n = 25). The 5-year survival of the entire cohort was 60.1%, with a median follow-up of 43 months. The 5-year survival for patients with percent predicted FEV1 stratified by more than 80%, 61% to 80%, 41% to 60%, and 40% or less was 70.1%, 59.3%, 52.5%, and 53.4%, respectively. The 5-year survival for patients with percent predicted Dlco stratified by more than 80%, 61% to 80%, 41% to 60%, and 40% or less was 70.2%, 63.4%, 44.2%, and 33.1%, respectively. In multivariable survival analysis, both larger tumor size (hazard ratio 1.15, p = 0.01) and lower Dlco (hazard ratio 0.986, p < 0.0001) were significant predictors of worse survival. The association of FEV1 and survival was not statistically significant (p = 0.18). CONCLUSIONS: Survival after lobectomy for patients with stage I non-small cell lung cancer is impacted by lower Dlco, which can be used in the risk and benefit assessment when choosing therapy.