In the graduation thesis, we have determined the proportion of green areas on a certain area with analysis of satellite images. Reviewed are areas of certain Slovenian cities and quarters of Ljubljana. A method for determining the borders of cities is described. The archive of satellite images is very extensive and access to them is simple and free. For our analysis, we have downloaded the data from satellites Sentinel-2A, Landsat 5 and Landsat 8. We have determined the greenness of surfaces with the calculation of normalized difference vegetation index (NDVI). Based on the results, we could determine how green are the Slovenian cities and what is the proportion of green areas in the city. We performed three analyzes, namely a comparison between six Slovenian cities (Ljubljana, Maribor, Celje, Kranj, Novo mesto and Koper), a comparison between four city quarters of Ljubljana (Center, Bežigrad, Šiška and Moste) and an analysis of changes in greenness of Ljubljana in the period from 1987 to 2017. For each analysis, there are maps with NDVI values and borders of areas in the results. There are also added Histograms of NDVI values.