The objective of our paper was to present changes in grassland in Poland and their impact on milk production in Polish agriculture. This topic is very important because Poland increased its milk production after integration into the European Union. At the same time, the area of grassland decreased. This caused the appearance of some environmental problems. More land became devoted to other usage such as roads and business. During 2007-2017 the area of permanent meadows in Poland (-3,8%), and pastures (-4,8%) decreased. In 2005-2017, although cow numbers decreased 25,8%, milk production increased 11,83% and milk yield per cow increased 50,2%. The changes in milk production caused concentration of this production mainly in three woivodeships in Poland: Podlaskie, Mazowieckie and Wielkopolskie. The situation in the milk market was created by many factors, among which elimination of the quota system is very important. This led to more milk production but allowed farmers to increase exploitation of grasslands.