The study was conducted in Awash National Park (ANP), which is located alongrnthe Addis Ababa-Djibouti highway. The study focused on the invasion of exoticrnalien species Prosopis juliflora (Sw.) DC. into ANP and the changes on speciesrncomposition and soil characteristics that have occurred as a result of therninvasion. Eight border site locations from the four directions (north, south, eastrnand west) were chosen. A total of 32 sites were sampled from which 80 quadratsrnwere established. From all quadrats plant species were collected and categorizedrninto trees, shrubs, sapling, seedling, herbs and grasses. The structure of woodyrnspecies including regenerations were described through the analysis of speciesrndiversity, density, frequency, DBH, height, Basal area and IVI. Percentage groundrncover of herbs and grasses was included in the analysis. Soil data were collectedrnfrom 32 sampling sites and analyzed for the selected parameters. A total of 122rnplant species representing 79 genera and 30 families were recorded. Sites with P.rnjuliflora had the highest diversity index and richness than sites without P.rnjuliflora. Highest number of woody species (60%) falling under the lowest DBHrnclass. Species under this DBH class includes P. juliflora, Acacia. oerfota, A. tortilisrnand Grewia schweinfurthii. Similarly, majority of the individuals (83.16%) of thernspecies prevailed in lower height class. Particularly, the height distribution of P.rnjuliflora was found only in the lower class. It might show that the invasion is justrncoming into the ANP. As compared to the other woody species in reference withrnfrequency rank, density and IVI values P. juliflora was among the top threernspecies, next to A. oerfota and A. senegal. The population distribution patterns ofrnsix important tree species bordering ANP reveals three types of diameter classrndistribution pattern and P. juliflora found under inverted J-shaped distributionrnpattern. The analysis from the regeneration status of P. juliflora implies therndistribution of more seedling population than that of sapling and maturernindividuals. The analysis from ground cover percentage indicated that sites withrnP. juliflora had the highest percentage cover than sites without P. juliflora. Resultsrnfrom distribution of P. juliflora revealed that from the total of 80 sampling plots, P.rnjuliflora was recorded in 19 plots (47.5%), out of which 9 (18.75%) were foundrninside the park. The invasion of P. juliflora towards the ANP is in the southrndirection, particularly along Sogedo site. The analysis from soil result indicatesrnthat except on some cations, mean values of the rest of the soil parameters underrnstudy were not significantly changed (p