A herpetofauna list of the mountains of Balcarce and Mar del Plata cities. A list of four species of Amphibians and sixteen species of Reptiles collected during four years at the ridge of mountains of Balcarce and Mar del Plata cities, is given. Brief comments about their ecology is also given. The presence of the colubrid Pseudablabes agassizii at Buenos Aires province is confirmes and two new Iguanidae of the genus Liolaemus are presented.