A phase IV clinical trial, multicentric (3 Hospitals in Madrid) controlled, prospective, open and randomized of long-term treatment with hypertonic saline in cystic fibrosis patients. The purpose of this study is to verify if the long term inhalation (48 weeks) of major volume (10 ml) increases the free time without pulmonary exacerbation, and if this increase is superior to the obtained with the inhalation of the standard volume (5 ml) that has been advocated.

Inclusion Criteria:

• Clinical diagnosis of Cystic fibrosis
• Over 6 years old
• FEV1 over than 30%
• Must be able to perform a spirometry
• Must be able to perform induced sputum
• Must tolerate the maximum dose of 10 ml hypertonic saline
• No oral neither intravenous treatment within the previous 2 weeks before the beginning of the study
• No treatment with hypertonic saline in the 2 weeks before

Exclusion Criteria:

• No clinical diagnosis of Cystic Fibrosis
• No tolerance of 10 ml of hypertonic saline
• Positive pregnancy test
• No tolerance of Beta2-agonist
• Treatment with corticosteroids
• FEV1 < 30%
• Liver and/or lung transplantation
• Oxygen treatment
• Hospital admission within the 4 previous weeks
• Oral or intravenous antibiotic treatment within the 2 previous weeks
• Smokers
• Pulmonary colonisation with Burkholderia cepacia complex