This study was conducted in the Hallideghie Wildlife Reserve (HWR), North-East Ethiopia, with the aim to describe woody species composition and community types in the area. Vegetation data were collected from 66 (20 m × 20 m) plots established along five transect lines that were stratified across major vegetation types. Community types were identified using cluster analysis, and species richness, evenness and diversity were computed and compared among community types. A total of 53 woody plant species belonging to 32 genera and 16 families were identified. Fabaceae, with 16 species (~30%) and seven genera (22%), was the most dominant woody plant family in the reserve, while the majority of the families were represented by one or two species and genera. Five community types were identified in the reserve, which not only differed in their species composition, but also in their species richness, evenness and Shannon diversity. These findings may indicate that the different community types have been subjected to varying types and levels of abiotic and biotic factors. Prosopis juliflora, an invasive alien species, appeared to be one of the most dominant woody species, at least, in two of the five community types, indicating that this species is, and will be, likely posing serious threats to vegetation and ecosystem of the reserve. In conclusion, this study has provided the first useful ecological information on vegetation composition and diversity in the HWR that would serve as an input for management decisions.