Background: Cystic fibrosis is the most common life-limiting genetic condition in Caucasians and the life-expectancy of those newly diagnosed is increasing. Inspiratory muscle training may be a way of improving the lung function and quality of life of people with cystic fibrosis. Hence there is a need to establish whether this intervention is beneficial. Objectives: To determine the effect of inspiratory muscle training on health-related quality of life, pulmonary function and exercise tolerance. Search methods: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials register comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Date of most recent search: 08 July 2013. Selection criteria: Randomised or quasi-randomised clinical controlled trials comparing different inspiratory muscle training regimens with each other or a control in people with cystic fibrosis. Data collection and analysis: Three review authors independently applied the inclusion and exclusion criteria to publications and assessed the quality of the included studies. Main results: Fourteen studies were identified. Of these eight studies with 180 participants met the review inclusion criteria. There was wide variation in the quality of the included studies. Data were not published in sufficient detail or with sufficiently similar outcome measures in these studies to perform meta-analyses. Authors' conclusions: We have not found any evidence to suggest that this treatment is either beneficial or not. We would advise that practitioners evaluate on a case-by-case basis whether or not to employ this therapy. We recommend that future studies make more use of health-related quality of life and exercise tolerance measures; and that there is an agreement upon a single standard measure of classifying the clinical status of the participants.