Exacerbations of asthma are episodes that require a change in treatment. Treatments of exacerbations are planned gradually according to the needs of the patients. Magnesium sulphate (MgSO₄) -either intravenous (IV) or nebulised- is a treatment option that is used with increasing frequency in patients with severe exacerbations of asthma who do not respond to the initial treatment. MgSO₄ may have bronchodilatory and an anti-infl ammatory eff ects in the airways. Both nebulised and IV forms of MgSO₄ seem to be eff ective in children. However, the effi cacy of nebulized MgSO₄ is limited in adults. IV MgSO₄ can be used in adults who suff er from a severe exacerbation and who do not respond to the initial treatment. MgSO₄ has no major side eff ects and is a cost eff ective treatment that benefi ts patients in addition to the conventional treatments in severe exacerbations. In this review, the role of MgSO₄ in exacerbations of asthma was presented with the data obtained from the recent studies and meta-analyzes.