the purpose of this work is to estimate the density and the population size of four primate species [alouatta clamitans cabrera, 1940; callicebus nigrifrons (spix, 1823); callithrix aurita (é. geoffroy, 1812); cebus nigritus (goldfuss, 1809)] which occur in a fragment of atlantic forest of approximately 350 hectares located in pouso alegre, state of minas gerais, as well as to give subsidies for the conservation of those species in the area. the population surveying was carried out through the distance sampling method in linear transects (distance sampling). data were collected between april and august 2008 from four transects deployed in the study area. the density and population size were calculated using the software distance 5.0 and were estimated in 23,83 ± 9,78 ind./km2 for callicebus nigrifrons, 14,76 ± 5,92 ind./km2 for callithrix aurita and 7,71 ± 2,13 ind./km2 for cebus nigritus. the population size was estimated in 83,0 ± 34,0 individuals for c. nigrifrons, 52,0 ± 20,8 individuals for callithrix aurita and 27,0 ± 7,4 individuals for cebus nigritus. with regard to the howler monkey (a. clamitans), it was stated out that just a group with six individuals survive in the area. in conclusion, the chances for these isolated populations to survive are slim due to the risk of stochastic events. the creation of ecological corridors connecting the study area to the other fragments, besides the translocation of individuals from other areas of the atlantic forest to this region, could provide alternatives to ensure the viability of these populations in a long-term. therefore, it is necessary to consolidate public policies in pouso alegre that lead to the creation, enlargement and management of conservation units and incentives for the adoption of productive practices based on sustainability in these areas of ecological interest.