The diet and activity patterns of a group of black howler monkeys (Alouatta caraya) were monitored on the left bank of the Aquidauana river over 11 months, from September 2008 to July 2009. The group was composed of eight individuals, two adult males, three females and three immature including subadults and infants. Quantitative data were collected using scan sampling method for 5 minutes with an interval of 15 minutes. The general activities budget (n = 6434 records) was 64.7% rest, 18.5% travel, 10.1% feeding, 4.4% for social behavior and 2.3% for miscellaneous behaviors. The level of rest was similar to patterns of genus (64.7%). The diet (n = 606 records) was composed mainly of leaves (72.8%) and flowers (14.8%) and supplemented by fruits (8.2%) and buds (4.2%). The consumption of reproductive parts of plants, especially flowers, was relatively high by the standards of southerly populations of the species. Members of the group rested significantly less than feed during the rainy season. The diet was marked by the consumption of leaves throughout the study. The consumption was higher in the dry at flowers (17.8%) and fruits in the rainy season (12.9%). It also registered a substantial difference in the behavior of adults and immature individuals, where the first rested significantly more, but spent less time in other categories: food, travel and social interactions. Given this, it's likely that the general budget was under the influence of group's composition, where there was a predominance of mature members, a typical pattern in the genus. The results indicate patterns of behavior and diet that are typical to the genus but marginal for the species. The contrasts can be related mainly to the geographic location of the area of the study, the ecotone Cerrado-Pantanal, and concomitant ecological differences. There is a clear need to continue the studies of A. caraya in the Bororo region, not only for a more systematic assessment of their ecological patterns, but also to contribute to the development of conservation strategies. Keywords: black-howler-monkeys; animal biology; behavioral ecology; activity patterns. (n = 6434 registros) foi de 64,7% para o descanso, 18,5% para o deslocamento, 10.1% para alimentação, 4,4% para o comportamento social e 2,3% para comportamentos não mutuamente exclusivos. O nível de descanso foi similar aos padrões do gênero (64,7%). A dieta (n = 606 registros) foi composta, principalmente por folhas (72,8%) e flores (14,8%) e completada por frutos (8,2%) e brotos (4,2%). O consumo de partes reprodutivas de plantas, principalmente flores, foi relativamente alto para os padrões das populações mais meridionais da espécie. Os membros do grupo descansaram significativamente mais e se alimentaram menos na estação chuvosa em relação à seca. A dieta foi marcada pelo consumo de folhas ao longo do estudo. A ingestão de flores foi significativamente maior na estação seca (17,8%) e a de frutos na chuvosa (12,9%). Foi registrada, também, uma diferença considerável no padrão comportamental d...