Acute bronchiolitis is the most common reason for hospitalization of infants during winter. A hypothesis for the effectiveness of epinephrine may be that it exerted an effect on overall infant respiratory mechanics by reducing nasal edema. We studied the effect of drop epinephrine (as a decongestant) with drop Nacl0.9% (as a placebo) on 100 patients between 1 to 12 months with the episode of wheezing, diagnosed as bronchiolitis who need to O2 therapy and admission in hospital. Before treatment the clinical condition (O2 saturation, respiratory rate, heart rate, retraction, dyspenea and wheeze) was evaluated. The first group (A) received routine treatment of bronchiolitis (O2 therapy, salbutamol spray and neubulizer) and also recieved drop phenyephrin 0.5% in supine position that remained in this position for 1 min. The second group (B) received routine treatment of bronchiolitis (O2 therapy, salbutamol spray and neubulizer) and also recieved drop NaCl 0.9% in supine position that remained in this position for 1 min. This is a double blind study. Both drops were colorless and smell less and labile as A and B. Thirty minutes after administration of drug and placebo, O2 saturation, respiratory rate, heart rate, retraction, dyspenea and wheeze were evaluated and scored.