The study on the diversity of mammalian fauna in Borena-SayintrnNational Park (BSNP), South Wollo Zone, Ethiopia was conducted fromrnDecember, 2009 to April, 2010. The study area was divided into riverinernforest, erica woodland and open grassland habitats based onrntopography during the preliminary survey. The altitude of the arearnranges from 1900m to 3699m asl. Representative sample sites wererntaken from each habitat type and surveyed using random linetransectrnmethod. Twenty three species of medium to largesized, five species ofrnrodents and two species of shrews were identified and recorded fromrnBSNP. Small and largesized Sherman traps and snaptraps were used torntrap small mammals and morphometric measurement was taken forrnthe species. From a total of 88 small mammals trapped caught,rnL.flavopunctatus had the highest relative abundance (37.7%), followedrnby P.harringtoni and O.typus with 17% each. S.albipes, A.dembeensisrnand C. flavescens had 12.5%, 8% and 5.7% of abundance, respectively.rnC.fumosa had the lowest relative abundance (2.3%). Mammals of thernstudy area were classified in to common (33.4%), uncommon (23.3%),rnoccasional (16.7%) and rare (26.7%) based on how often they werernsighted or evidences recorded. They were also categorized into meatrneaters (33.3%), small gleaners (16.7%), fruit and leaf eaters (13.3%) andrnothers (36.7%). For large mammal survey, indirect methods such asrnfeaces, hairs, spines, puge marks, sound and carcass were used inrnaddition to the direct observations. Major threats of the Park identifiedrnduring the study period were grass collection, livestock grazing andrnencroachment.rnKey words/ Phrases: Borena-Sayint National Park, conservationrndiversity, mammals