Impaired mucociliary clearance characterises lung disease in cystic fibrosis (CF). Hypertonic saline enhances mucociliary clearance and may lessen the destructive inflammatory process in the airways. This is an update of a previously published review.To investigate efficacy and tolerability of treatment with nebulised hypertonic saline on people with CF compared to placebo and or other treatments that enhance mucociliary clearance.We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register, comprising references identified from comprehensive electronic database searches, handsearches of relevant journals and abstract books of conference proceedings. We also searched ongoing trials databases.Date of most recent searches: 08 August 2018.Randomised and quasi-randomised controlled trials assessing hypertonic saline compared to placebo or other mucolytic therapy, for any duration or dose regimen in people with CF (any age or disease severity).Two authors independently reviewed all identified trials and data, and assessed trial quality. The quality of the evidence was assessed using GRADE.A total of 17 trials (966 participants, aged 4 months to 63 years) were included; 19 trials were excluded, three trials are ongoing and 16 are awaiting classification. We judged 14 of the 17 included trials to have a high risk of bias due to participants ability to discern the taste of the solutions.Hypertonic saline 3% to 7% versus placeboAt four weeks, we found very low-quality evidence from three placebo-controlled trials (n = 225) that hypertonic saline (3% to 7%, 10 mL twice-daily) increased the mean change from baseline of the forced expiratory volume at one second (FEV1) (% predicted) by 3.44% (95% confidence interval (CI) 0.67 to 6.21), but there was no difference between groups in lung clearance index in one small trial (n = 10). By 48 weeks the effect was slightly smaller in one trial (n = 134), 2.31% (95% CI -2.72 to 7.34) (low-quality evidence). No deaths occurred in the trials. T...