Abstract The availability of accurate data on forest resources is an essential requirement for species documentation, community identification, and planning within the context of sustainable use of the forest. A survey of mammalian species was conducted in Yotyet/Yewezera Forest southern Ethiopia to assess their diversity and abundance in the area. Transect method was used to collect data for the study. Data was collected from the established line transect in each habitat from February 2019 to April 2019. A total of 553 individuals of 10 medium and large sized mammalian species distributed in to five orders and six families were recorded. Chlorocebus aethiops (42.9%) was the most abundant mammalian species followed by Colobus guereza (22.2%). Leptus starcki (1.6%), Traglaphus scriptus (2.9%), Crocuta crocuta (3.3%) were the less abundant species. The highest diversity of mammals was recorded from open grassland (H´=2.082; Simpson´s index of diversity (1-D) = 0.8626) and the less was from human plantations area (H´= 1.044; Simpson´s index of diversity (1-D) = 0.6311). Though, Yotyet/Yewezera community forest is with high potential of conserving biodiversity, it is not free from anthropogenic factors that threatened the biological components of it. Therefore, awareness should be created for the local people about the effects of forest destruction on the wildlife and start biodiversity conservation program in the area. Key words: Abundance, diversity, mammals, Yotyet/Yewezera forest, Southern Ethiopia