Objective: To review systematically the magnesium sulphate (MgSO4) dosing regimens tested in low and middle income countries (LMICs) for women with preeclampsia (prevention) and/or eclampsia (treatment). Data Sources: We searched Medline, EMBASE, IPA, CINAHL, CDSR, and CENTRAL databases for relevant English language publications. Study Selection: Our search yielded 753 publications, of which 26 (10 randomized controlled trials and 16 observational studies) evaluated MgSO4 for preeclampsia and/or eclampsia in World Bank-classified LMICs. Data Extraction: Independent, by two authors. Data Synthesis: Twenty-five studies were conducted in hospital settings and one in the community. Rates of eclampsia were usually < 5% (median 3.0%, range 0.0% to 26.5%) even when MgSO4 was administered for eclampsia. When dosage varied from the standard Pritchard or Zuspan regimens, almost all (n = 22) reduced the dose or duration of treatment, most commonly because of concerns about maternal safety, cost, or resource availability. Four trials of a loading dose only (4 g IV + 10 g IM) versus loading plus maintenance dosing of 5 g/4 hr IM found no difference in eclampsia recurrence (RR 1.64; 95% CI 0.48 to 5.65, n = 396). One study documented less eclampsia recurrence associated with community administration of a MgSO4 loading dose before referral to a care facility versus treatment in a care facility (RR 0.23; 95% CI 0.11 to 0.49, n = 265). Conclusion: Use of MgSO4 for eclampsia treatment and prevention has been well-studied in LMICs, but concern remains about potential toxicity. Further studies are needed to identify the minimum effective dosage of MgSO4 for management of preeclampsia and eclampsia and whether MgSO4 loading can be safely administered in the community.