Hypertensive diseases of pregnancy are among the first causes of severe maternal morbidity and mortality especially in developing countries. In developed countries, eclampsia is a rare event, but remains responsible for a significant maternal mortality. For over a century, magnesium sulfate is widely used in the United States in many obstetric indications including the treatment of eclampsia crises. There appears to be no consensus to treat or prevent seizures by magnesium sulfate. However, a large, multicentre, randomised trial compared the efficacy of magnesium sulfate with diazepam or phenytoin in eclamptic women. In this trial, magnesium sulfate was associated with a significantly lower rate of recurrent seizures and lower rate of maternal death than that observed with other anticonvulsants. The main objective of magnesium sulfate prophylaxis in women with preeclampsia is to prevent or reduce the rate of eclampsia and complications associated with eclampsia.However, several arguments balance a wide use of magnesium sulfate: the prevalence of eclampsia in the Western world is very low, the use of magnesium sulfate does not affect the neonatal morbidity and mortality, and it is associated with a high rate of side effects, sometimes severe, such as respiratory depression. Prescription the magnesium sulfate must depend the benefit / risk is directly correlated to theprevalence of eclampsia in the risk group considered report. Despiteseveral meta-analyzes and randomized studies methodologically unassailable with proven benefits in the treatment and prevention of eclampsia, despite the Guidelines for Clinical Practice of several learnedsocieties have formalized its Terms of Use, the use of this molecule remains controversial. Many obstetricians consider that the risks of this treatment outweigh the benefits. This raises questions on the role of this treatment in preventing the occurrence of eclampsia. We report three cases of poisoning by magnesium sulfate in the trea