To determine the response of nebulized magnesium sulfate on the lung function of acetylcholine-induced asthma children. Three hundred and thirty children of asthma with positive bronchial provocation test were randomly divided into three groups: magnesium sulfate, albuterol, and a combination of magnesium sulfate and albuterol. Lung function was compared between the three groups. Forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF) as percentage over predicted at 10 min and 20 min in albuterol and combination group were significantly improved when compared to magnesium group. The changes in FEV1 and PEF expressed as absolute and percentage over predicted was not statistically significant from baseline to 20 min in magnesium, albuterol, and combination of magnesium sulfate and albuterol. There was no significant adverse effect observed during the present study. Nebulized magnesium sulfate alone has a bronchodilatory effect in Ach-induced asthmatic children. The combination of MgSO4 and albuterol did not has a synergistic effect.