The Atlantic Forest is recognized as a global hotspot for having one of the highest rates of endemism and biodiversity. Its portion in the state of Rio de Janeiro is extremely fragmented and reduced. The present study seeks to get information on the non-volant mammals of RPPN Rio das Pedras in municipality of Mangaratiba, state of Rio de Janeiro. The rapid mammal's survey was accomplished by the use of pitfalls, live traps, transects and camera traps. We recorded 23 non-volant species that represent 13.1 % of Rio de Janeiro’s terrestrial mammal species. Among the recorded species, five are endemic of the Atlantic Forest and three are in the state list of threatened or presumably threatened species. The area presents great mammal richness, but the hunting activity and the presence of exotic species may represent a threat to the local biodiversity and should be controlled.