MgSO4 is routinely used in therapeutics despite its toxicity. The aim of the present review was to compare MgSO4 and MgCl2 effects in order to answer the question whether MgSO4 could be or not replaced by MgCl2. Considering that the two salts have both similar and proper effects, a clear-cut conclusion is not easy to draw. However, choosing MgCl2 seems advisable because of its more interesting clinical and pharmacological effects and its lower tissue toxicity as compared to MgSO4.