Objective: To evaluate the maternal-neonatal outcome in magnesium (Mg)-intoxicated women with preeclampsia with severe features (PESF) treated with magnesium sulfate (MgSO 4 ). Methods: A total of 19 Mg intoxicated PESF women (cases) were compared with 166 PESF women without signs of intoxication (controls). Results: Mg serum levels of cases was higher compared to control group (12.36 ± 3.54 mg/dl versus 2.69 ± 0.83 mg/dl). 3 women died and 3 had major maternal morbidity in cases group compared with zero in the control group (P = 0.009). Mg intoxication was also significantly associated with perinatal deaths and low Apgar scores at 1 and 5 minutes. Conclusion: Mg intoxication is associated with a increased risk of maternal and perinatal mortality and morbidity.