The accurate identification of taxa of Aotus is essential for 1) the development of precise biomedical assays, 2) the determination of potential illegal traffic of this genus, and 3) conservation. Although many studies have contributed to what we know about the phylogenetics of Aotus, none used a sufficiently large number of samples to clarify its complexity. To address this need, we sequenced 696 base pairs of the mitochondrial cytochrome-oxidase II gene (mtCOII) in 69 specimens of 7 taxa of Aotus. We also analyzed 8 microsatellite loci in 136 individuals of 6 taxa. In contrast to previous studies, we sampled only wild individuals and have a precise geographical origin for each one. The mtDNA results showed that: 1) the northern gray-necked group of Aotus is genetically more homogeneous than the polyphyletic red-necked group of Aotus; 2) the ancestors of Aotus vociferans seem to be the original species candidate for the current Aotus; 3) Aotus azarae azarae and A. a. boliviensis are the most differentiated taxa, likely a result of extreme genetic drift during stasipatric speciation; 4) the first genetic splits found among taxa of Aotus occurred during the Pliocene (or even Miocene) while the most recent ones happened during the Pleistocene, when forest refugia may have played an important role in speciation. The mean number of microsatellite alleles was 3-5.33 alleles per locus. We found some private alleles that could be useful in helping to identify illegal trade, although a larger sample size is needed to ensure that these alleles are really private to the relevant taxa. These new findings increase our understanding of the phylogeny of Aotus and the level of genetic diversity within different taxa of Aotus. © 2011 Springer Science+Business Media, LLC.