The Cordillera de los Frailes is a mountainous region in the central parts of the Bolivian Andes.

It consists of mainly two parts: the western region is a volcanic field of subhorizontal, undeformed ignimbrites dating back to upper Miocene, about 5 to 23 million years from today; the eastern part, the so-called Maragua Syncline which is much older, is a mountain range of sedimentary rock of Cretaceous-Paleocene origin in a north–south thrust.

The Cordillera de los Frailes borders Poopó Lake in the northwest and stretches between a line Challapata-Macha-Ravelo in the north and Río Mulato-Potosí-Betanzos in the south.

Because of the landlocked location, the Cordillera de los Frailes gives rise to only a few rivers of supraregional importance.

The main river of the region is the Pillkumayu which crosses the area from northwest to southeast.