| Opole Silesia/Opolian Silesia | |
| Native Name: | |
| Type: | Historical region |
| Subdivision Type: | Country |
| Subdivision Name: | Poland |
| Seat Type: | Historical capital |
| Seat: | Opole |
| Population Density Km2: | auto |
| Timezone: | CET |
| Utc Offset: | +1 |
| Timezone Dst: | CEST |
| Utc Offset Dst: | +2 |
Opole Silesia or Opolian Silesia[1] (Polish: {{audio|LL-Q809 (pol)-KaMan-Śląsk Opolski.wav|Śląsk Opolski, also known as Opolszczyzna, German: Oppelner Schlesien, Ôpolski Ślōnsk, Czech: Opolské Slezsko), is a loosely defined historical region of Poland, part of Upper Silesia.
Throughout a large part of its history, the region had been ruled by the Duchy of Opole and other Silesian Duchies, formed as a result of the medieval fragmentation of Piast-ruled Poland. Following the Silesian Wars the region found itself within Prussia, and from 1871 it was also part of Germany. Following Germany's defeat in World War II in 1945, in accordance with the Oder–Neisse line, Opole Silesia became again part of Poland.