The Osława (Czech: Oslava, German: Oslawa, Ukrainian: Ослава) is a river in South-Eastern Poland.

The main villages along the Osława are, from source to mouth: Balnica, Czaszyn, Duszatyn, Jawornik, Kulaszne, Maniów, Mików, Mokre, Morochów, Prełuki, Rzepedź, Smolnik, Szczawne, Tarnawa Dolna, Turzańsk, Wola Michowa, Wysoczany, Zagórz and Zasław.

The Osława valley must have been an important trade route and human settlement axis as early as 9th or 10th century.

The region then became a site of contention between Poland, Kievan Rus and Hungary starting in at least the 9th century.

Before World War II, the Osława line, was designated as the wild frontier between Poles and Lemkos.