BACKGROUND: Most acute wheezing episodes in preschool children are associated with rhinovirus. Rhinovirus decreases extracellular adenosine triphosphate levels, leading to airway surface liquid dehydration. This, along with submucosal edema, mucus plaques, and inflammation, causes failure of mucus clearance. These preschool children do not respond well to available treatments, even oral steroids. This calls for pro-mucus clearance and prohydration treatments such as hypertonic saline in wheezing preschool children. METHODS: Randomized, controlled, double-blind study. Forty-one children (mean age 31.9 Â± 17.4 months, range 1-6 years) presented with wheezing to the emergency department were randomized after 1 albuterol inhalation to receive either 4 mL of hypertonic saline 5% (HS) (n = 16) or 4 mL of normal saline (NS) (n = 25), both with 0.5 mL albuterol, twice every 20 minutes in the emergency department and 4 times a day thereafter if hospitalized. The primary outcome measured was length of stay (LOS) and the secondary outcomes were admission rate (AR) and clinical severity score. RESULTS: The LOS was significantly shorter in the HS than in the NS group: median 2 days (range 0-6) versus 3 days (range 0-5) days (P = .027). The AR was significantly lower in the HS than the NS group: 62.2% versus 92%. Clinical severity score improved significantly in both groups but did not reach significance between them. CONCLUSIONS: Using HS inhalations significantly shortens LOS and lowers AR in preschool children presenting with an acute wheezing episode to the emergency department.