A census of ungulates was carried out in May 2002 in the Haut Niger National Park, Republic of Guinea. The study site was subdivided into three census blocks in which a total 111 transects (total length = 838.24 km) were censused once by one observer. Densities were estimated using DISTANCE analysis. We observed a total of 10 species of ungulates (nine Bovidae and one Suidae). Maxwell's duiker Cephalophus maxwelli had the highest density (3.69 individuals km−2) followed by the red-flanked duiker Cephalophus rufilatus (2.61 individuals km−2), whereas the buffalo Syncerus caffer had the lowest density (0.34 individuals km−2). Compared to a census in 1997, the abundance of red-flanked and Maxwell's duikers significantly decreased (by c. 50%) whereas that of other species remained stable or increased. This variation may possibly be explained by a change in the hunting pattern in the area, which shifted from large-scale hunting by large groups of hunters from outside the area before the Park's creation, to small-scale poaching by local hunters. The Park includes a diversity of ungulate species and harbours populations of ungulates that are important at both national and regional levels. We recommend therefore that the Park should be considered a key area for the conservation of ungulates in West Africa.