Abstract: We compared the genetic patterns - genetic diversity, population structure, and demographic history - of two African colobine species - King Colobus (Colobus polykomos) and Western Red Colobus (Piliocolobus badius) - in Taï National Park (TNP), Ivory Coast, and Cantanhez Forests National Park (CFNP), Guinea-Bissau, using a dataset of microsatellite loci. While TNP is the largest and best preserved forest of West Africa, CFNP is highly fragmented. Thus, these two forests provide the opportunity of studying the impact of forest status on the maintenance of these species' evolutionary potential. CFNP colobines showed very low genetic diversity, while the populations in TNP still maintain high levels of genetic diversity. A strong signal of population decline was and we found no clear signal of population decrease in Western red colobus and a limited decrease in King colobus. These results suggest larger and historically more stable populations in TNP compared to CFNP. We cannot exclude the possibility that the demographic effects resulting from the recent increase of bushmeat hunting are not yet detectable in TNP using genetic data. Nevertheless, the fact that the TNP colobus populations are highly genetically diverse and maintain large effective population sizes suggests that well-preserved forests are crucial for the maintenance of populations, species and probably for the evolutionary potential in colobines. Methods: Blood-derived DNA samples of eight King Colobus (Colobus polykomos) and 20 Western Red Colobus (Piliocolobus badius) were genotyped for eleven and ten, respectively, human-derived nuclear microsatellite loci. Loci were amplified by Polymerase Chain Reaction (PCR), following the protocol optimised by Minhós et al. (2013). PCR products were analysed using an ABI 3130XL Automatic Sequencer at the Genomics Unit of Instituto Gulbenkian de Ciência, Portugal. Alleles were scored using GeneMapper® Software version 4.1 (Applied Biosystems). Each locus was genotyped up to three times per sample and two independent observers scored the genotypes. Genotypes were considered as heterozygous after each allele was observed in at least two independent PCR reactions. This dataset presents the consensus genotypes obtained for each individual at each locus. No GPS data are available for this dataset, although all individuals are known to come from Taï National Park, Ivory Coast. Usage notes: The dataset corresponds to two CSV files - one for King Colobus (Colobus polykomos) and another for Western Red Colobus (Piliocolobus badius). The header shows microsatellite names (2 columns per microsatellite, as these are diploid individuals) and each subsequent row corresponds to an individual. The first column exhibits the codes of the individuals. Missing data is coded as 0.