Olsztyn Voivodeship (Polish: województwo olsztyńskie) was an administrative division and unit of local government in Poland in the years 1946–75, and a new territorial division between 1975–1998, superseded by Warmian-Masurian Voivodeship. Its capital city was Olsztyn.
From 1946 to 1975 the Olsztyn Voivodeship covered a larger area.
Warmian–Masurian Voivodeship is a voivodeship (province) in northeastern Poland. Its capital and largest city is Olsztyn. The voivodeship has an area of 24,192 km (9,341 sq mi) and in 2019 had a population of 1,425,967.
Warmian–Masurian Voivodeship was created on 1 January 1999 from the entire Olsztyn Voivodeship, the western half of Suwałki Voivodeship, and part of Elbląg Voivodeship, pursuant to the Polish local government reforms adopted in 1998. The province's name derives from two historic regions, Warmia and Masuria, although also parts of other regions are located within the province, i.e. of Chełmno Land, Powiśle, Mazovia, Bartia and Natangia.