This trial aims to analyze whether the inhalation of hypertonic saline combined with a positive expiratory pressure (PEP) device increases the amount of sputum expectorated during the chest physiotherapy session ( inhalation + bronchial drainage).

All patients will perform two different arms of treatment in a crossover randomization. Each arm of treatment will be applied during 5 consecutive days. The wash-out period will be one week. Before starting the trial all patients will do an inhalation formation.

During the study period the patients' pharmacological treatment remains unchanged

Inclusion Criteria:

• Pass the inhalation test
• Chronic sputum production, at least ≥ 10 ml /24h
• Cystic Fibrosis (CF) diagnosed ( established by genotype or sweat sodium>70 mmol/l or sweat chloride of>60 mmol/l)
• Clinically stable at the time of recruitment (defined as no requirement for antibiotics or change in respiratory medication in the preceding 4 weeks)
• Trained in the use of autogenic drainage technique (at least 6 months)
• Inhaling hypertonic saline since at least 6 months
• To be able to provide written, informed consent and perform the protocol and the evaluations

Exclusion Criteria:

• Active massive hemoptysis during the previous 2 months
• Patient in transplantation or retransplantation list
• Patient already participating in another study at the same time