The distal convoluted tubule (DCT) is the shortest segment of the nephron and consists of an early (DCT1) and late part (DCT2). Here, several transport proteins, like the thiazide-sensitive NaCl cotransporter (NCC) and the epithelial magnesium (Mg(2+)) channel (TRPM6), are exclusively expressed. This makes the DCT the major site of active transcellular Mg(2+) reabsorption determining the final excretion in the urine. Following the Mg(2+) influx via the apically localized TRPM6, intracellular Mg(2+) diffuses to the basolateral membrane where it is extruded to the blood compartment via still-unidentified Mg(2+) transporters. Recent years have witnessed multiple breakthroughs in the field of transcellular Mg(2+) reabsorption. Epidermal growth factor and estrogen were identified as magnesiotropic hormones by their effect on TRPM6 activity. Intracellularly, receptor of activated protein kinase C 1 and adenosine triphosphate were shown to inhibit TRPM6 activity through its alpha-kinase domain. Furthermore, dysregulation or malfunction of transcellular Mg(2+) reabsorption in DCT has been associated with renal Mg(2+) wasting. Mutations in TRPM6 are responsible for hypomagnesemia with secondary hypocalcemia. A defect in the gamma-subunit of the Na(+)/K(+)-adenosine triphosphatase causes isolated dominant hypomagnesemia resulting from renal Mg(2+) wasting. Moreover, in Gitelman's syndrome, mutations in NCC also result in impaired transcellular Mg(2+) reabsorption in DCT. This review highlights our recently obtained knowledge concerning the molecular regulation of transcellular Mg(2+) reabsorption.