The main objective of this study was to improve the DEM produced from SRTM90 by using the interpolation methods existing in MATLAB software. There are three types available of interpolations; bicubic, bilinear, and nearest neighbor interpolation methods. Using these methods does not require much effort or software to produce high DEM resolutions which can be rise up to about or smaller than 10 meters DEM resolution. In the current study, actual data of SRTM90 and SRTM30 was used for a part of USA concerned only with the area between 40ºN to 41º N latitudes and 105º W to 106º W. The MATLAB interpolation methods used in this study can be easily used to sampling SRTM90 files into different types of DEM resolutions which can be easily convert 0.000833 arc-degrees resolution (SRTM90) to 0.000104 arc-degrees or less. The results obtained indicated extremely good improvement by using the bicubic sampling process besides its effortless.