Objective: Objective of this study was to assess the impact of deranged renal function and severity of disease in terms of number of fits and mean arterial pressure on incidence of toxicity of MgSO4 and to compare the standard regimes of Magnesium sulfate by IM and IV routes. Method: A prospective study was performed on patients of eclampsia and severe preeclampsia. Result: Subjects with creatinine levels > 0.80 mg/dl, mean arterial pressure ≥ 130 mmHg and No. of fits >3 have significantly higher percentage of patients with loss of DTR (p value = 0.002; 0.05; 0.04 respectively). At higher creatinine levels >0.80 mg/dl significantly less percentage of patients with loss of DTR were found (p value = 0.009) with IV route compared to IM route. At mean arterial pressure ≥ 130 mmHg and No. of fits >3 results were comparable with IM and IV routes of MgSO4. Conclusion: IV route was found safer in patients with higher creatinine values. But with further increase in severity as evident by mean arterial pressure ≥ 130 mmHg and No. of fits >3 route of MgSO4 did not matter.