The diversity of Brazilian vertebrates is regarded among the highest in the world. However, the biological diversity is still mostly unknown and a good part of it is seriously threatened by human activities. This study aimed to inventory the medium and large size mammals present in the Reserva Biológica de Santa Rita do Sapucaí, an Atlantic forest reserve located in Santa Rita do Sapucaí, southeastern Brazil. Sand-plots, photographic traps and searches for animal tracks on pre-existent trails in the area, were carried out once every two months between May 2006 and February 2007. The sand-plots and tracks were inspected during five consecutive days per sampling. We obtained 108 records of 15 species, mostly of carnivorans. Two confirmed species are threatened with extinction in Brazil (Callithrix aurita and Leopardus pardalis). The results suggest that the sampled reserve has high species richness and plays an important role in conservation of mammals in this landscape, including species threatened with extinction.