Magnesium ion (Mg(2+)) and calcium ion (Ca(2+)) control a diverse and important range of cellular processes, such as gene transcription, cell proliferation, neoplastic transformation, immune response and therapeutic treatment. Their characteristic biologic antagonism makes it important to treat the most important aspects of that competitive behavior together. This synopsis aims to be a useful means of promoting further research on the relationship between both cations and human health affected by environmental conditions.