The aim of this project was to determine the amount of forest degradation between the year of 1987 and 2001 and investigate the compatibility of Landsat TM for forest degradation. To achieve the purposes stated above Landsat TM images acquired on 25 September 1987 and 2 July 2000 were used. Digital image processing techniques were executed in order to assess forest degradation and examine the appropriateness of Landsat TM data for the study. To evaluate and visualize the tendency, quantity and impact of changes in the forest area, classification procedure was utilized and matrix analysis was carried. As a result of this analyses, temporal changes of general land cover/use classes especially forest areas were examined for the Asian side of Istanbul.