© 2018 European Cystic Fibrosis Society Background: The cystic fibrosis transmembrane conductance regulator (CFTR) potentiator ivacaftor is approved for patients with CF with gating and residual function CFTR mutations. We report the results of an observational study investigating its effects in CF patients with non-G551D gating mutations. Methods: Patients with non-G551D gating mutations were recruited to an open-label study evaluating ivacaftor. Primary outcomes included: lung function, sweat chloride, weight gain, and quality of life scores. Results: Twenty-one subjects were enrolled and completed 6 months follow-up on ivacaftor; mean age was 25.6 years with 52% <18. Baseline ppFEV 1 was 68% and mean sweat chloride 89.6 mEq/L. Participants experienced significant improvements in ppFEV 1 (mean absolute increase of 10.9% 95% CI = [2.6,19.3], p = 0.0134), sweat chloride (−48.6 95% CI = [−67.4,-29.9], p < 0.0001), and weight (5.1 kg, 95% CI = [2.8, 7.3], p = 0.0002). Conclusions: Patients with non-G551D gating mutations experienced improved lung function, nutritional status, and quality of life. This study supports ongoing use of ivacaftor for patients with these mutations.