The Mongolian gazelle ( Procapra gutturosa ) is a representative ungulate species of Mongolia that inhabits steppes. Their number and range decreased during the last century, and the population has been suffered from occasional demographic changes caused by human and environmental factors. During the summer of 2005, we obtained genetic samples from gazelle carcasses encountered along the international railroad between Russia and China, to examine genetic diversity and its changes in relation to historical demographic shifts. Gazelle genetic structure and diversity were investigated using mitochondrial control region sequence. In the phylogenetic analysis, we confi rmed that there are two genetic groups unrelated to geographical location. We also showed the genetic structure of gazelles was unrelated to existence of the railroad. Based on the genetic diversity indices and demographic parameters, the population was suggested to have experienced demographic expansion historically, and effect of known demographic decline was not detected.