Ostrołęka is a town in northeastern Poland on the Narew river, about 120 km northeast of Warsaw. Situated in the Masovian Voivodeship (since 1999), previously capital of Ostrołęka Voivodeship (1975-1998). Currently capital of both Ostrołęka County and Ostrołęka city County.
In 1807 it was the site of a Napoleonic victory by the French general Nicolas Charles Oudinot.
The Battle of Ostrołęka of 26 May 1831 was one of the largest battles of the Polish November Uprising. Throughout the entire day, the Polish forces under Jan Skrzynecki fought for the control over the town of against the assaulting Russian imperial forces of Hans Karl von Diebitsch.