The purpose of this study was to carry out an inventory of medium and large-sized mammal species occurring in the Mata Atlântica State Park (MASP). Located in Água Limpa municipality, state of Goiás, the MASP occupies an important area with a seasonal forest remnant, which is considered an enclave of the Atlantic Forest within the Cerrado biome. From October 2012 to December 2013, MASP’s area was randomly surveyed for evidence of mammal presence. Records of 23 species of wild mammals were obtained, seven of them listed as nationally endangered. Medium and large-sized mammal species composition is characteristic of the Cerrado biome, and no endemic species of the Atlantic Forest were recorded. Richness and diversity of the mammal species recorded in MASP show the importance of this protected area for in situ conservation.