GOR is increased in cystic fibrosis (CF), however, its prevalence, characteristics, association with gastric aspiration and respiratory impact are not well characterized. We investigated acid and weakly acidic (WA) reflux, aspiration and respiratory ymptoms/function in adult CF patients. Methods: Thirty-three CF patients [19men; 29(18-55) years, (10 post LTx)] underwent impedance-pH monitoring for detection of acid (pH<4) and WA GOR (pH4-7). In 16 patients cough was objectively recorded with oesophageal manometry, and the Symptom Association Probability (SAP) was calculated. Saliva and Bronchoalveolar Lavage Fluid (BALF) were tested for bile acids (BA). Results: Twenty-eight patients had increased GOR (21acid, 5WA and 2acid+WA) and 10 had a positive SAP for reflux-cough. GOR parameters were similar in non-LTx and post-LTx CF patients. The sequence reflux-cough was significantly more common than cough-reflux. 16/38 patients had BA in saliva and 6/10 in BALF and this was almost exclusively observed in patients with genotype DF508/DF508. Only 12/28 with increased GOR and 9/22 with BA in saliva/BALF had typical reflux symptoms. There was a positive correlation (r=0.53, p=0.03) between oesophageal acid exposure and cough. SAP-positive patients with for reflux-cough had a lower lung function than SAP-negative patients. Conclusion: Increased GOR is prevalent in CF and not secondary to cough. Acid GOR is common, but WA GOR may also occur. CF patients have a high risk for aspiration and reflux seems to be associated with more cough and poorer lung function. Outcome studies with intense anti-reflux therapy are needed to confirm the deleterious role of reflux in CF progression.