A double-blind randomized controlled trial was conducted to examine the efficacy of nebulized magnesium sulfate in the treatment of acute exacer-bation of asthma in children. Thirty patients received nebulized salbutamol (0.15 mg/kg; minimum dose 2.5 mg) with 2.0 mL of isotonic magnesium sulfate solution and another 30 patients received same dose of salbutamol with 2.0 mL of normal saline on 3 occasions at 20 min intervals. Mean percent of predicted peak expiratory flow rate (PEFR) detected in both group at 0 min were not significantly different. But from 10 min up to 60 min, the values were significantly different among the groups. Mean respiratory rate at 0 and 10 min were similar in both groups and from 20 up to 60 min, respiratory rate improvement were significantly different. Arterial oxygen saturation (SaO2) at presentation was not significantly different. But from 10 min up to 60 min differences were significant. With single dose of nebulization, in the magnesium sulfate with salbutamol group, by 20 min almost all (29 out of 30) patient achieved at least 60% of predicted PEFR. Within this 20 min, from control group none could achieve 60% of predicted PEFR. After 2nd dose of nebulization control group started achieving 60% PEFR value. Regarding response criteria, with 2nd dose of nebulization, at 30 and 40 min 9 (30.0%) and 17 (56.7%) patient from magnesium sulfate with salbutamol group showed good response (PEFR ≥70% predicted). But within this first 40 min time, none could show good response in control group. With 3rd dose of nebulization all from magnesium sulfate group showed good response but even at 60 min, 4 (13.3%) patient in control group failed to be included as good responder. So, it is evident that nebulization by isotonic magnesium sulfate solution with salbutamol provide early and better response as compared to conventional approach (salbutamol plus normal saline) in acute exacerbation of asthma in children.