Although many studies have reported improvement in lung function following LVRS, the magnitude of improvement and subsequent decline has not been evaluated against medical therapy after the second year. Methods: Existing pulmonary function records were collated for each participant since randomisation from the Brompton LVRS trial cohort. Longitudinal data analysis was used to profile the history of medically treated patients and the effect of LVRS. Results: Pulmonary function results were collated from survivors over a median of 25 (17 to 39) months. The estimated immediate increase in mean FEV1 following surgery was + 0.259 l (0.179, 0.339), with a rate of change of - 0.005 l (- 0.009, - 0.001) per month compared to medical therapy (p < 0.001). The changes in the secondary outcome measures (LVRS compared to medical therapy) were an increase in FVC (p = 0.004), decrease in RV (p < 0.001) and TLC (p < 0.001), with differences that were maintained over time. The initial reduction in RV/TLC ratio was sustained (p < 0.001), but the estimated initial increase in peak flow was accompanied by a gradual decline that was not statistically significant (p = 0.062). KCOc showed no immediate change, but there was a gradual sustained increase with time (p = 0.009). Mean oxygen saturations improved and continued to do so compared to patients on medical therapy (p = 0.001). Conclusion: The immediate increase in FEV1 is not sustained, although the mechanical improvements of LVRS on increasing FVC, reducing both the RV and RV/TLC ratio, appear to be maintained. The important benefits of LVRS may be the gradual and sustained increase in transfer factor accompanied by improved oxygen saturations.