Ostroh (Ukrainian: Остро́г; Russian: Остро́г, Ostrog, Polish: Ostróg) is a historic city located in Rivne Oblast (province) of western Ukraine, located on the Horyn River. Ostroh is the administrative center of the Ostroh Raion (district) and is itself designated as a special administrative subordination within the oblast. The current estimated population is around 14,801 (as of 2001).