This study provides for the first time a detailed list of anuran species from Serra do Ouro Branco, southernmost Espinhaço Mountain Range, state of Minas Gerais, southeastern Brazil. We present data from monthly field surveys made between 2006 and 2007 and data from sporadic surveys conducted between 2003 and 2006. We recorded 47 species, corresponding so far to one of the highest frog richness known for a single location in Minas Gerais. We recorded typical species from the Atlantic Forest (19) and Cerrado (6) morphoclimatic domains; species restricted to the Espinhaço Range (8); or opened areas in mountainous regions (4); and widely distributed species (10). The Serra do Ouro Branco corresponds to the southernmost record of six species, besides holding important populations of other species with restricted geographic distributions. The high richness of frog species and the actual threats to which species are subject make the adoption of conservation measures in the region an emergency action.