Introduction: ETI treatment highly impacts on clinical outcomes in pwCF. While compassionate studies shed a light on real-life impact on severe pwCF, prospective real-life data in moderate, mild pwCF need further exploration. Aims and objective: to evaluate in a real-life setting adult pwCF after 6 months of ETI treatment (T6), to explore differences between pwCF with different categories of impairment of baseline (T0) ppFEV1. Methods: LCI2.5, ppFEV1, sweat chloride (Clsw), BMI, 6MWT were collected at T0 and at T6. Results: 126 adult pwCF were included (males 41%, mean age 28.9±11.2, F/F 37%, baseline ppFEV1 72.4±17.9, LCI2.5 16 ±4.6, BMI 20.4 ±2.7 kg/m2). At T6, ppFEV1, BMI, 6MWT significantly increased, LCI2.5% and Clsw decreased. Mild correlations were found between changes in ppFEV1 and LCI2.5%. Improvement in LCI2.5% was more evident in F/MF compared with F/F, while other outcomes did not change. Increase in BMI was greater in pwCF with baseline ppFEV1 40-59 and 60-79 compared with baseline ppFEV1 ?80; exacerbation rate was higher at T0 and decreased more in pwCF with ppFEV1 40-59 at T0. Worse ppFEV1 and LCI2.5% at T0 characterized patients with greater responses in ppFEV1; these patients also had greater improvements in LCI2.5% and BMI at T6. Conclusions: As expected, all observed outcomes improved after 6 months of ETI treatment in adult pwCF. A greater response in ppFEV1 was found in patients with worse respiratory function at T0; greater improvement in LCI2.5% was shown in pwCF with greater ppFEV1 response. The gain in BMI was greater in pwCF with worse ppFEV1 at T0; this might relate to better respiratory status.