Warmian-Masurian Voivodeship, or Warmia-Masuria Province (in Polish: Województwo warmińsko-mazurskie, ), is a voivodeship (province) in northeastern Poland. Its capital and largest city is Olsztyn. The voivodeship has an area of 24,192 km2 (9,341 sq mi) and a population of 1,427,091 (as of 2006).
The Warmian-Masurian Voivodeship was created on January 1, 1999, out of the former Olsztyn Voivodeship and parts of Suwałki and Elbląg Voivodeships, pursuant to the Polish local government reforms adopted in 1998. The province's name derives from two historic regions, Warmia and Masuria.
The province borders the Podlaskie Voivodeship to the east, the Masovian Voivodeship to the south, the Kuyavian-Pomeranian Voivodeship to the south-west, the Pomeranian Voivodeship to the west, the Vistula Lagoon to the northwest, and the Kaliningrad Oblast (an exclave of Russia) to the north. The region contains the southern part of East Prussia, which Poland took over from Germany in 1945, while the Soviet Union took over the northern part, the present Kaliningrad Oblast.
The Warmian-Masurian Voivodeship has the largest number of ethnic Ukrainians living in Poland due to forced relocations (such as Operation Vistula) carried out by the Soviet and Polish Communist authorities.