ABSTRACT. We here investigated the kin structure and pattern of dispersal in the black-and-gold howler monkey (Alouatta caraya, Platyrrhini, Atelidae) based on genotype differences at nine microsatellite loci of 48 individuals from eight social groups along the riparian forest of the Tocantins River, Brazil. The genetic diversity (H E = 0.647) was similar to or higher than previously reported values in other Alouatta species. Given that no spatial kinship structure was detected, we found no evidence that dispersal was constrained by distance within the spatial scale analyzed (<25 km). Although no evidence was found for sex-biased dispersal, our results strongly suggest that extra-group copulations are common in A. caraya, and that both males and females disperse from their natal group.