The relatively scarcely known Zakouma National Park serves as a real sanctuary for Chad's Sudanese fauna owing to the possibility of permanent access to standing water throughout the dry season. With a density of elephants approaching an animal per square kilometre this protected area is exceptional for the species in West Africa. A census by systematic sample counts from the air in 2002 showed that the numbers of most species of large herbivore had increased from those of 1986. A new census using the same method was undertaken during the 2008 dry season with the aim of acquiring another estimate of the numbers of the large mammal species and to verify recent reports of an upsurge in elephant poaching. Comparison of the two censuses shows that large mammal populations were stable or increasing for all species except elephant that showed a drastic decline. Evidence of poaching on a large scale, including the presence of numerous recent carcasses, is enough to explain this decline. Although some species, waterbuck and topi, occupied the same areas in both censuses others, buffalo, roan antelope and hartebeest, had ranges that extended farther west in the park in 2008. (Résumé d'auteur