Reduced to a tiny fraction of its original area, much of the Atlantic Forest habitat remaining in eastern Brazil is distributed in small, isolated patches on private land. The potential role of these fragments in the conservation of the region's primate fauna is poorly understood. As part of a study of buffy-headed marmosets Callithrix flaviceps in Minas Gerais, forest remnants were visited in order to evaluate this potential. Marmosets were observed in one-third of the sites and may exist in up to 60 per cent of forest patches in the region. A second threatened primate, the brown howler monkey Alouatta fusca, may occur in one-quarter of the sites visited. The muriqui Brachyteles arachnoides was not encountered. Overall, the survey suggests that, with appropriate management, privately owned forest fragments may play an increasingly important role in the conservation of the Atlantic Forest's fauna in this and other regions.