This study compared the efficacy and safety of nebulized magnesium sulphate with salbutamol to normal saline with salbutamol as the initial treatment of severe acute asthma patients. The present study was designed as a randomized open controlled clinical trial. The study was conducted Mymensingh Medical College Hospital over a period of 11 months from December 2009 to October 2010. Patients admitted with severe acute asthma having inclusion criteria were the study population. Among 120 study population 60 were in salbutamol with magnesium sulphate group and 60 were in salbutamol with normal saline group. The study finding showed that peak flow at baseline was similar in two groups. At 10 minutes after nebulization, the mean±SD percentage increase in peak flow was greater in magnesium sulphate group (20±4%) than in the normal saline salbutamol group (13±3%). At 20 minutes the percentage increase in peak flow was greater in magnesium sulphate group (35±7%) than in the normal saline salbutamol group (24±6%) p value <0.001. Magnesium sulphate plus salbutamol group reached PEF near to 60% which is not in saline salbutamol group. There was no significant changed in respiratory rate, pulse rate, systolic, diastolic blood pressure and clinical evidence of unwanted adverse effect.