Nebulization with B-agonist and administration of systemic corticosteroids are standard treatments for severe asthma exacerbations, but corticosteroids take several hours to become effective. IV magnesium sulphate (MgSO4) acts faster and has both antiinflammatory and bronchodilating properties. It appears to have played a pivotal role in the successful management of a child with severe asthma exacerbation and atelectasis unresponsive to conventional therapy. A literature review reveals that the results of IV MgSO4 are much greater in children than in adults, and can avoid the need to hospitalize 25% of children presenting with severe asthma. Magnesium sulphate appears safe to use.