Background: Respiratory failure secondary to recurrent respiratory infections is the most common cause of death in Cystic fibrosis (CF). Objectives: To assess the efficacy of noninvasive positive pressure ventilation (NIPPV) on respiratory function, use of accessory respiratory muscles, ease of physiotherapy for respiratory clearance, quality of sleep and nutritional status in CF patients with respiratory failure. Methods: All CF patients admitted to the pediatric department of Masih Daneshvari hospital, Tehran from March 2015 to January 2016 were studied. The inclusion criteria were clinical evidence of respiratory distress and signs of respiratory acidosis. The exclusion criteria were nausea and vomiting, not tolerating NIPPV, need for intubation, pneumothorax, presence of giant bullous emphysema or decreased level of consciousness. Baseline spirometry and venous blood gas (VBG) was obtained before and after NIPPV. A simple questionnaire was filled out for the nutritional status, sleep quality, ease of physiotherapy for airway clearance and the volume of secretions after NIPPV compared to baseline. Paired samples t-test and Wilcoxon Signed Rank test in SPSS version 16 were used for the before and after comparison of numerical and ordinal variables, respectively. Results: Out of a total of 53 CF hospitalized patients 17 met the inclusion criteria. There were 10 (58.8%) males and 7 (41.1%) females