The objective of this study was to investigate the effectivenesses of nebulized salbutamol, epinephrin, 3% saline, and normal saline (0.9% NaCl) in the treatment of mildly affected infants with acute bronchiolitis. We enrolled 186 children (mean age 9.5 +/- 5.3 months, range 1.5-24 months, 65.1% male) with a first episode of wheezing diagnosed as mild bronchiolitis in emergency department. Patients were randomized in a double-blind fashion to receive 4 ml dose either of 1.5 mg epinephrine plus normal saline (group 1; n = 38) or 1.5 mg epinephrine plus 3% saline (group 2; n = 39) or 2.5 mg salbutamol plus normal saline (group 3; n = 36) or 2.5 mg salbutamol plus 3% saline (group 4; n = 36) or normal saline alone (group 5; n = 37) at 0 and 30 min. Thus, all treatment modalities included high amount of NaCl (72-240 mg). Clinical score, oxygen saturation and heart rate were assessed at 0, 30, 60, and 120 min. After discharge, patients were reassessed by telephone contact at 48 hr and 6 months. The baseline characteristics were similar in all groups (P > 0.05). The outcome of patients at 120 min was found significantly better than the baseline values (P < 0.05). There were no significant differences between the outcome variables of the groups (P > 0.05). No adverse effects attributable to nebulized therapy were seen. In conclusion, all treatment modalities used in this study, including a total of 8 ml normal saline inhalation at 30-min interval showed clinically significant and swift improvement in mildly affected ambulatory infants with acute bronchiolitis.