Stadium OSiR w Olsztynie (OSiR Stadium in Olsztyn) is a multi-use stadium in Olsztyn, Poland. It is currently used mostly for football matches and is the home ground of OKS 1945 Olsztyn. The stadium has a capacity of 16,800 people.

The stadium was built in the 1970s. In 1994–2002, Stomil Olsztyn played its games in Polish First League there. On 24 June 1989 a game of the Polish Cup between Jagiellonia Białystok and Legia Warszawa (2:5) was played on the stadium. The match was watched by 20,000 fans. On 24 September 1997 venue also hosted friendly football match between Poland and Lithuania (2:0).

53°46′22.89″N 20°30′33.88″E / 53.7730250°N 20.5094111°E / 53.7730250; 20.5094111