Digital elevation model (DEM) is a digital representation of the surface topography of thernearth. Apart from visualization of o 3D surface topography of the earth, DEM is very usefulrndata source to perform various analyses. DEM can be generated from wide range sourcesrnincluding land survey, Photogrammetry and remote sensing satellites. SRTM 30m DEM byrnThe Shuttle Radar Topography mission (SRTM), the global digital elevation model byrnAdvanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER GDEM) and arnglobal surface model called ALOS Worldview 3D 30 meter (AW3D30) by Advanced LandrnObserving Satellite (ALOS) are satellite based global DEMs freely available, open sourcernDEM datasets. The specified accuracy of these dataset is often uneven within each datasetrndue to various reasons including radar characteristics, type of topography in differentrnregions and physical properties of the surface. This study aims to assess the vertical accuracyrnof ASTER GDEM2, SRTM 30m and ALOS (AW3D30) global DEMs over Ethiopia in twornstudy areas-Addis Ababa and Dire Dawa by using DGPS points and other available accuraterntopographic reference data. The method used to assess the vertical accuracy of those DEMsrnrange from simple visual comparison to relative and absolute comparisons providingrnquantitative assessment that used the elevation differences between DEM datasets andrnreference datasets.rnThe vertical accuracy of DEMs assessed in three stages based on the reference datasets used.rnThe first vertical accuracy test is done by taking the residual from elevation differencingrnbetween GPS points and DEM elevation values at the location of every GPS points. Thernresult of this assessment showed better accuracy of SRTM 30m DEM (having RMSE of 5.14rnm and 6.35 m in Addis Ababa and Dire Dawa Study areas), and closely followed by ALOSrn(AW3D30) DEM which scored RMSE of 5.34 m and 6.33 m in Addis and Dire study areasrnrespectively. ASTER GDEM 2 showed the least accuracy by scoring RMSE of 13.27 m inrnAddis Ababa and 11.41m in Dire Dawa study areas.rnThe second test was done by DEM (image) differencing (by subtracting every pixel of DEMsrnfrom every pixel of Reference DEM, which gives us the elevation residual). The result fromrnthis method assessment gave us RMSE values of 17.2 m, 4.5 m and 4.7 m in Addis Ababa forrnASTER, SRTM and ALOS DEMs respectively; RMSE of 9.7 m, 5.43 m and 5.74 m in DirernDawa Study area for ASTER, SRTM and ALOS DEMs respectively. This also shows the betterrnaccuracy of SRTM 30m DEM over the other two at least for this study. The third accuracyrnassessment was done by analysis of derived products such as slope and drainage network.rnThis also resulted in better quality of derived products for SRTM and ALOS DEM thanrnASTER GDEM. This concludes SRTM 30m and ALOS (AW3D30) DEM can be used for slopernclassification and Drainage or watershed delineation in this regions.