The main objective of this paper is to use satellite images to determine deforestation occurred in İstanbul as a result of rapid urbanization and anthropologic impacts between 1975 and 2000. Fort his reason, Landsat MSS images of 1975 and Landsat ETM + images of 2000 were evaluated. The method for comparison of postclassification was conducted for determining the change detection. In the classification stage of satellite data, Landsat MSS images vvith low resolution and GIS process \vere used for high accuracy and vvas reached overall 90 % accuracy for ali classes for both images. By using change matrices, changes in forest areas put forth together with spatial and area distribution.