The discovery of DMT1 (divalent metal transporter 1, also named as Nramp2-nature resistance-associated macrophage protein 2, or DCT1-Divalent cation transporter 1) is the most important breakthrough in the field of mammalian iron metabolism in recent years. It was first identified on the basis of its homology to Nramp1 in 1995. In 1997, two groups independently identified DMT1 as the first mammalian transmembrane iron transporter. Since then, considerable research effort has been devoted to studying this newly discovered protein and the understanding of DMT1 has been greatly imporved. The current knowledge of DMT1 is summarized, including its distribution, structure and different splice forms, expression regulation, physiological function and relationship between the disruption of its expression and the pathogenesis of some diseases.