Bronchiolitis is infection of the bronchial and bronchiolar epithelium, which is mainly caused by respiratory syncytial virus (RSV). The primary treatment remains largely supportive, with mechanical ventilatory support as needed [ 1 x 1 American Academy of Pediatrics Subcommittee on Diagnosis and Management of Bronchiolitis. Diagnosis and management of bronchiolitis. Pediatrics. 2006; 118: 1774–1793 Crossref | PubMed | Scopus (699) | Google Scholar See all References 1 ]. Other types of treatment remain controversial [ 1 x 1 American Academy of Pediatrics Subcommittee on Diagnosis and Management of Bronchiolitis. Diagnosis and management of bronchiolitis. Pediatrics. 2006; 118: 1774–1793 Crossref | PubMed | Scopus (699) | Google Scholar See all References , 2 x 2 Wright, RB, Pomerantz, WJ, and Luria, JW. New approaches to respiratory infections in children: bronchiolitis and croup. Emerg Med Clin North Am. 2002; 20: 93–114 Abstract | Full Text | Full Text PDF | PubMed | Scopus (30) | Google Scholar See all References ]. It has been shown that nebulized hypertonic saline (HS) decreases the hospital length of stay (LOS) as compared with normal saline (NS) among infants hospitalized with viral bronchiolitis [ 3 x 3 Kuzik, BA, Al‐Qadhi, SA, Kent, S et al. Nebulized hypertonic saline in the treatment of viral bronchiolitis in infants. J Pediatr. 2007; 151: 266–270 Abstract | Full Text | Full Text PDF | PubMed | Scopus (114) | Google Scholar See all References , 4 x 4 Zhang, LJ, Mendoza‐Sassi, RA, Wainwright, C et al. Nebulized hypertonic saline solution for acute bronchiolitis in infants. Cochrane Database Syst Rev. 2008; 8 (CD006458) Google Scholar See all References ]. We and other researchers demonstrated that nebulized HS and bronchodilators decreased symptoms and LOS for infants with mild to moderate viral bronchiolitis [ 5 x 5 Mandelberg, A, Tal, G, Witzling, M et al. Nebulized 3% hypertonic saline solution treatment in hospitalized infants with viral bronchiolitis. Chest. 2003; 123: 481–487 Crossref | PubMed | Scopus (121) | Google Scholar See all References , 6 x 6 Tal, G, Cesar, K, Oron, A et al. Hypertonic saline/epinephrine treatment in hospitalized infants with viral bronchiolitis reduces hospitalization stay: 2 years experience. Isr Med Assoc J. 2006; 8: 169–173 PubMed | Google Scholar See all References , 7 x 7 Luo, Z, Liu, E, Luo, J et al. Nebulized hypertonic saline/salbutamol solution treatment in hospitalized children with mild to moderate bronchiolitis. Pediatr Int. 2010; 52: 199–202 Crossref | PubMed | Scopus (52) | Google Scholar See all References ]. Both of the aforementioned studies used three times per day dosing, which is significantly less than the three to six times per hour regimens often used to children in respiratory distress [ 8 x 8 Wainright, C, Altamirano, L, Cheney, M et al. A multicentre, randomized, double‐blind, controlled trial of nebulized epinephrine in infants with acute bronchiolitis. N Engl J Med. 2003; 349: 27–35 Crossref | PubMed | Scopus (178) | Google Scholar See all References , 9 x 9 Patel, H, Platt, RW, Pekeles, GS et al. A randomized controlled trial of the effectiveness of nebulized therapy with epinephrine compared with albuteral and saline in infants hospitalized for acute viral bronchiolitis. J Pediatr. 2002; 141: 818–824 Abstract | Full Text | Full Text PDF | PubMed | Scopus (69) | Google Scholar See all References , 10 x 10 Ray, MS. Comparison of nebulized adrenaline versus salbutamol in wheeze associated with respiratory tract infection in infants. Indian Pediatr. 2002; 39: 12–22 PubMed | Google Scholar See all References ]. Children with moderate to severe bronchiolitis have difficulty in breathing. Frequently inhaled nebulized HS reduced the LOS for infants with moderately severe bronchiolitis [ 3 x 3 Kuzik, BA, Al‐Qadhi, SA, Kent, S et al. Nebulized hypertonic saline in the treatment of viral bronchiolitis in infants. J Pediatr. 2007; 151: 266–270 Abstract | Full Text | Full Text PDF | PubMed | Scopus (114) | Google Scholar See all References 3 ]. The present study was performed to investigate frequently inhaled nebulized HS for moderate to severe bronchiolitis in a prospective, randomized, double-blind, controlled fashion. The primary objective was to compare the symptoms, signs, clinical severity scores and the LOS of these infants with those of a control group of infants receiving frequently inhaled nebulized NS.