Medium resolution images are quite useful for environmental monitoring of large areas. Although there is no clear definition of what medium corresponds to in terms of spatial resolution of satellite imagery and other remotely sensed products, there is a consensus among environmental scientists that all pictures with pixel size approximately between 1,000 m and 100 m can be considered as medium resolution images. It should be pointed out that the definition is somewhat subjective, and certainly what is nowadays accepted as medium or high resolution can become a low resolution product in the near future, as advances in remote sensing technologies are very rapid. Numerous satellite missions are devoted to the monitoring of Earth’s surface at medium resolution and provide global products. Their usefulness merely depends on the revisit time, the time series available, the ease of data access, the cost, and certainly the quality assurance and verification of data. From this point of view, the products from the MODerate resolution Imaging Spectroradiometer (MODIS) on board NASA’s Aqua and Terra satellites are state of the art monitoring materials. This chapter presents various environmental applications of MODIS products.