Polesia, Polesie or Polesye ( Paliessie, Polissia or Polisia, , Poles'e ) is a natural and historical region of Eastern Europe. One of the largest forest areas on the continent, Polesie is located in the south-western part of the Eastern-European Lowland, the Polesian Lowland. On the western side, Polesie originates at the crossing of the Bug River valley in Poland and the Pripyat River valley of Western Ukraine. Polesie extends eastward through modern-day south Belarus and north Ukraine, and ends within Russia. The swampy areas of central Polesie are known as the Pinsk Marshes (after the major local city of Pinsk). Large parts of the region were contaminated after the Chernobyl disaster and the region now includes the Chernobyl Exclusion Zone and Polesie State Radioecological Reserve, named after the region.

Polesia, Polesie or Polesye ( Paliessie, Polissia or Polisia, , Poles'e ) is a natural and historical region of Eastern Europe. One of the largest forest areas on the continent, Polesie is located in the south-western part of the Eastern-European Lowland, the Polesian Lowland. On the western side, Polesie originates at the crossing of the Bug River valley in Poland and the Pripyat River valley of Western Ukraine. Polesie extends eastward through modern-day south Belarus and north Ukraine, and ends within Russia. The swampy areas of central Polesie are known as the Pinsk Marshes (after the major local city of Pinsk). Large parts of the region were contaminated after the Chernobyl disaster and the region now includes the Chernobyl Exclusion Zone and Polesie State Radioecological Reserve, named after the region.