A regional inventory of the anuran fauna of the mountainous areas of the municipality of Yopal (Casanare-Colombia) is presented. Aspects of their regional distribution and natural history of the species are reported. Individually in each locality studied, inventories showed that the number of species is relatively low, between 4-17, but the accumulative values for the piedmont region of the Orinoco totals 26 species in eight families and 15 genera. These values permit the evaluation of species richness thresholds obtained in previous studies of this group in the Andean foothills of the Orinoco River Basin. Assemblages found, are a mosaic of species from the eastern savannas that have occupied intervened environments in mountainous areas, together with a set of endemic species of the humid forests of the piedmont of the Colombian Orinoco.