Background: Magnesium sulfate (Mgso4) is still the drug of choice in both prophylaxis and active management of women with eclampsia. Different regimens of its administration have emerged for many years, but not thoroughly investigated. Objective: Is to outline the lowest adequate dose of Mgso4 in controlling cases of severe preeclampsia, and prophylaxis against eclampsia. Methods: A comparative study analyzed two maintenance regimens of MgSO4 therapy used for the cases of severe preeclampsia, admitted to the Obstetrics & Gynecology Department, Benha University Hospital, Benha University during the period from March 2014 until January 2016. 95 patients were evaluated for eligibility; 35 women were excluded [Not meeting inclusion criteria (n=23) Declined to participate (n=12)] .After exclusion the study included 60 pregnant women presented to our casualty unit with criteria of severe preeclampsia. All included women initially received 4 grams of Mgso4 IV slowely over 20 minutes as a loading dose. Then the patients were subsequently startified into two groups :- Group A: included 30 patients: (given 4 grams on 250 ml ringer solution completed in 4 hours and repeated every 4 hours by IV drip only for 12 hours) as abbreviated regimen of MgSO4 in the postpartum course. Group B: included 30 patients received a full maintenance dose of MgSO4 (4 grams of MgSO4 on 250 ml ringer solution over 4 hours repeated every 4 hours by IV drip for 24 hours) in the postpartum period. Results: Our results showed substantial evidence supporting the employment of Mgso4 in both prevention and active managment of eclampsia. There was no significant difference between occurrence of eclampsia among the study groups after either administration of loading dose with maintenance dose for either 12 hours or 24 hours. Conclusion: Concerning the comparable potency, less side effects, easier monitoring and cost-effectiveness of the abbreviated regimen, 12 hours maintenance dose of Mgso4 in the management of preeclampsia is preferable to the full dose course administration.