Objectives: Chronic rhinosinusitis (CRS) is prevalent in the Cystic Fibrosis (CF) population. CRS exacerbations in CF are thought to contribute to pulmonary exacerbations. Literature regarding the impact of endoscopic sinus surgery (ESS) is inconclusive. This study examines rates of lung function decline and pulmonary exacerbation in CF patients who have undergone ESS. Design: Retrospective review of medical records. Setting: Academic Hospital. Participants: 40 adult CF patients. Main outcome measures: Rate of lung function decline (Forced Expiratory Volume1(FEV1) % predicted), number of pulmonary exacerbations (IV/oral antibiotic therapy +/- hospital admission) and total number days hospitalized 2 years post-operatively was collected. CRS patients undergoing ESS were matched to those without ESS by gender, age, and F508del genotype. Results: Forty patients (mean age 37.4, 60% male) were reviewed. No significant difference was found between the surgical group and controls in baseline FEV1(72.5% vs. 72.7%, p=0.98), 2-year pre-operative number of pulmonary exacerbations (3.05 vs. 1.65, p=0.10), or Lund-Mackay scores (12.25 vs. 11.55, p=0.71). No significant difference was found in 1-year (70.5% vs. 72.8%, p=0.84) or 2-year (70.4% vs. 72.6% p=0.80) post-operative FEV1 and 2-year post-operative pulmonary exacerbations (1.7 vs. 1.45, p=0.87). A significant increase was identified in total number days hospitalized post-operatively (4.85, p=0.02). In the surgical group, no significant difference was identified between preoperative and postoperative FEV1, 1 -year (-2.51%, p=0.32) and 2-years after ESS (-3.10%, p=0.51), postoperative rate of pulmonary exacerbations (-1.28, p=0.11), or in total number days hospitalized (3.74, p=0.14). Conclusions: In this study, ESS does not appear to significantly improve FEV1 or decrease the number of pulmonary exacerbations post-operatively.