Management of premenstrual syndrome (PMS) remains a challenge because of two difficulties. On the one hand, the establishment of the correct diagnosis and on the other hand, due to the polymorphism of the symptomatology. There are hypotheses that magnesium deficiency may explain many of the clinical symptoms of PMS. Magnesium is the co-factor of hundreds of enzymatic reactions and influences membrane stability and ion exchange. Both are fundamental physiological functions in many organs and systems.