In healthy individuals, Mg
2+ homeostasis is tightly regulated by the concerted action of intestinal absorption, exchange with bone, and renal excretion. The kidney, more precisely the distal convoluted tubule (DCT), is the final determinant of plasma Mg
2+ concentrations. Positional cloning strategies in families with hereditary hypomagnesemia identified defects in several proteins localized in the DCT as causative factors. So far, the identified actors involved in Mg
2+ handling in the DCT include: the transient receptor potential channel melastatin member 6, the pro-epidermal growth factor, the thiazide-sensitive Na
- cotransporter, the γ-subunit of the Na
+-ATPase, the hepatocyte nuclear factor 1B, the potassium channels Kv1.1 and Kir4.1, and the cyclin M2. In the years to come, the identification of new magnesiotropic genes and related proteins will further clarify the role of the kidney in Mg
2+ homeostasis, and will potentially lead to new therapeutic approaches for hypomagnesemia.