The Pacaya Samiria National Reserve has terra firma forest and seasonally-flooded forest (várzea) typical of the western lowland Amazon. It is very biodiverse and its natural resources are important for local populations and for subsistence and commercial hunters. In January 2013 and February 2016, we made two rapid surveys to assess population densities and biomass and evaluate habitat characteristics of the previously unstudied primate community at Katakari in the western part of the reserve. We surveyed six line transects and calculated density estimates using the Distance program. We also estimated crude and metabolized biomass for each primate species and the primate community as a whole. To characterize habitat in the area, we surveyed 9 km of strip transects (10 m width), collecting data on the abundance of tree species previously identified as food resources for the primates. We detected 11 primate species along 40.06 km of transect walks and estimated total primate density for the six species with sufficient detections at 164.9 ind/km2. Large-headed capuchins (Sapajus macrocephalus) had the highest density at 63.6 ind/ km2. We estimated crude primate biomass to be 534.8 kg/km2 and metabolized primate biomass at 401.32 kg/km2. We recorded 1,279 trees from 14 families, 28 genera and 43 species. The most common families were Sapotaceae and Fabaceae. The most common species were Inga spp., Attalea platerata and Chrysophyllum oliviforme. Primate densities and biomass were similar to those found in other areas of Pacaya Samiria. We found no correlation between primate diversity and tree DBH, height or crown projection, suggesting that habitat structure in the area may not be a determinant of primate diversity. As one of the most diverse in the world, the primate community in the Pacaya Samiria National Reserve is a priority for primate conservation in Peru.