Background: Short acting ß2-agonist is considered the main stay of therapy in acute asthma episodes, but it could not completely relieve the bronchospasm and reduce dyspnea. One of the other treatments is magnesium sulphate (MgSO4). Nebulized MgSO4 effect has been less evaluated in asthmatics.  Aim of the Work is to compare the effects of nebulized MgSO4 in higher doses versus salbutamol nebulization in severe asthmatic attacks. Patients and Methods: Two hundreds asthmatic patients with severe attacks were included in an interventional study. Following initial clinical evaluation and spirometric measurements especially peak expiratory flow (PEF) and Forced expiratory volume in the first second (FEV1) measurements (after control), patients were divided into two equal groups; group I: nebulized salbutamol and group II: nebulized MgSO4. Salbutamol group received salbutamol (2.5 ml)+saline (2.5 ml) while MgSO4 group received MgSO4 (500mg), 7.5 ml (2 mmol vial), through a jet nebulizer. The nebulizations were given 3 times for the first hour, 20 minutes apart, then hydrocortisone and oxygen if not improved then every hour for the remaining 4 hours. Clinical reevaluation, PEF and FEV1 remeasurement were done. Results: The pre-nebulizer clinical parameters, PEF and FEV1 were nearly similar between groups I and II: (PEF: 376.45±49.88 versus 388.46±43.22, respectively), (FEV1: 57.06±9.03 versus 56.51±9.18, respectively). The post-nebulizer PEF and FEV1 values between groups I and II were also nearly similar: (PEF: 410.98±273.82 versus 391.24±39.81, respectively, with p value 0.47), (FEV1: 62.22±9.52 versus 61.78±9.41, respectively, with p value 0.74); indicating the nearly equal effectiveness of both medications. However, the clinical parameters post-nebulization were different: group I developed tachycardia, palpitation and tremors as side effects while group II side effects included nausea, taste changes, numbness and dizziness.  Conclusion: Nebulized magnesium sulphate provides nearly equal response as compared to salbutamol in the treatment of acute asthmatic attacks in adults.