ASTER is a Japanese sensor which is one of the five equipments that are on board of the Terra satellite launched by NASA in 1999. The sensor has been collecting satellite imagery since 2000. The ASTER GDEM was released to the public after a joint operation between NASA and METI (Japan's Ministry of Economy, Trade and Industry). It is the most complete DEM of the earth ever made, covering 99% of its surface in 1 arc second resolution. The previous most comprehensive DEM, Shuttle Radar Topography Mission (SRTM) DEM, covered approximately 80% of the Earth's surface, with a resolution of 3 arc seconds, and 1 arc seconds. The GDEM covers the earth from 83 degrees North to 83 degrees South (SRTM's coverage is from 56 degrees S to 60 degrees N), becoming the first DEM that covers the Polar Regions. Nowadays the second version is in use, which is corrected and enhanced in terms of several artifacts. In spite of these corrections it is reported that there are still some artifacts such as wells and spikes in the data. In this study ASTER DEM and SRTM DEM are analyzed against local height data. The ground truth data is local DEMs created by using 25K national topographic maps. We will do an area based comparison between ASTER DEM, SRTM DEM and local DEMs. For this purpose we selected 37 25K map sheets randomly distributed over the country. Furthermore we create 3D visualizations and compare them in terms of detail richness of the topography. Finally it is concluded that SRTM DEM seems to be superior to ASTER DEM over the Turkish territory.