Background: To assess efficacy of nebulized magnesium sulphate in Bronchiolitis. Materials and Methods: Seventy- two patients age ranged 1 month to 24 months of acute bronchiolitis were divided into 2 groups of 36 each. Group I received nebulization with 3 mL of 3.2% magnesium sulphate (MgSO4) every 4 hourly for 24 hours and group I received standard care alone. Parameters such as BSS, respiratory rate (RR), peripheral capillary oxygen saturation (SpO2), heart rate (HR) were recorded before treatment and at 1, 2, 4, 8, 12, 16, and 24 hours post- operatively. The need for noninvasive ventilation, need for admission to intensive care unit (ICU) were also recorded