Abstract: Despite Ethiopia is among the few African countries with high mammal species diversity, its mammalian resource is highly deteriorating and there is little information about the mammalian resource. As a result, a study was carried out to determine the species composition, distribution and relative abundance of large wild mammals during dry and wet seasons from July 2010 to February, 2011 in and around Wondo Genet Forest. The study area was stratified into four habitat types (natural forest, plantation, wooded grassland and agro forestry) based on land-use and vegetation cover of the study area. Stratified systematic sampling method was used to lay line transects in each habitat type. Species identification and total counting of individuals were made along each transect. A total of 19 species of large wild mammals were recorded in the area. The commonest mammals were: Papio anubis. Chlorocebus aethiops, Colobus guereza and Tragelaphus scriptus meneliki. In terms of abundance, Papio anubis (48%) and Colobus guereza (32%) were the most abundant species, while Felis serval and Felis caracal were the least abundant that each contributed only less than 1% of the total observations. The highest Simpson’s Index of diversity (1-D) was obtained in the agro forestry habitat (0.769), while wooded grassland had the lowest (0.383). The seasonal variation in abundance (number) of individuals of large wild mammals was significantly different (χ2 = 153.309, df =1, p<0.05). However, the seasonal variation in species composition of large wild mammals was not significantly different (χ2 = 0.125, df = 1, p>0.05). Despite the study area is home for different species of mammals, livestock grazing, agriculture and human encroachments are very evident in the areas, putting an enormous strain on the flora and fauna. Hence, there is a need for urgent conservation measures to save the area.