From 2003 to 2005 we carried out surveys in Burkina Faso to investigate the status of primate taxa. In the south-west near the border with Côte d'Ivoire we discovered sooty mangabey Cercocebus atys, a primate species that had not been previously reported in the country. This population is the subspecies C. a. lunulatus, the white-naped mangabey, one of the 25 most threatened primate taxa. As the subspecies occurs in a gallery forest that is next to a wildlife safari hunting area, we recommend that hunting is prohibited near these forests. The recent creation of the Warigué protected area, linking the Comoé-Léraba Reserved Forest and Partial Wildlife Reserve in Burkina Faso where we observed the subspecies, with the Comoé National Park in Côte d'Ivoire, could make an important contribution to the survival of this, the northernmost population, of the subspecies.