Scientific inveStigAtionSStudy objectives: Weight gain and obesity are common after lung transplantation. Despite associations between these conditions and sleep disordered breathing (SDB) in the general population, the prevalence and clinical impact of SDB in lung transplant recipients is unknown. The study objective was to determine the prevalence and clinical correlates of SDB in a cohort of lung transplant recipients. Methods: Single-center cross-sectional study. Overnight polysomnography, sleep questionnaires, and anthropomorphic measurements were conducted on 24 lung recipients transplanted at least one year previously. The primary outcome was the prevalence of SDB, defined as an apnea-hypopnea index (AHI) ≥ 10 per hour. Results: The prevalence of SDB was 63%. Obstructive sleep apnea (OSA) was observed in 38% and central sleep apnea (CSA) in 25%. Among all subjects, the mean AHI was 19.7 ± 24.4 events/hour and the average weight gained after transplant was 10.5 ± 12.3 kg. Sub-jects with SDB had a higher systolic blood pressure (135 ± 12 vs. 124 ± 13 mm Hg, p = 0.045), body mass index (BMI) (28.2 ± 3.7 vs. 24.0 ± 4.0 kg/m 2 , p = 0.008) and arousal index (28.0 ± 26.9 vs. 10.4 ± 6.4 per hour, p = 0.025) compared to the non-SDB group. Cyclosporine use was associated with CSA (p = 0.006). Recipients with OSA had a greater change (pre to post transplant) in BMI (5.8 ± 4.6 vs. 2.0 ± 2.9 kg/m 2 , p = 0.05) compared with non-SDB subjects. Conclusions: Sleep disordered breathing is highly prevalent after lung transplantation. Polysomnography should be considered in lung transplant recipients, especially if they have gained weight.