|Named for: Ostrava City|
|Settlements||Ostravice, Frýdlant nad Ostravicí, Frýdek-Místek, Ostrava|
|Primary source||Bílá Ostravice|
|- location||Moravian-Silesian Beskids|
|- elevation||900 m (3,000 ft)|
|Secondary source||Černá Ostravice|
|- elevation||190 m (600 ft)|
|Length||64 km (40 mi)|
|Basin||827 km2 (319 sq mi)|
|- average||12.7 m3/s (448 cu ft/s)|
|- max||933 m3/s (32,949 cu ft/s)|
Ostravice (Polish: Ostrawica, German: Ostrawitza) is a river in Moravian-Silesian Region, Czech Republic. It originates in the Moravian-Silesian Beskids and then flows through Ostravice, Frýdlant nad Ostravicí, Frýdek-Místek and Paskov to Ostrava where it enters the Oder as its right tributary. It partly forms the border between historical regions Moravia (left bank) and Silesia (more precisely Cieszyn Silesia) (right bank).
The river starts as the Ostravice after the confluence of the Bílá Ostravice (i.e., White Ostravice, considered its main source) and the Černá Ostravice (i.e. Black Ostravice). They are both streams flowing through deeply forested valleys which are important access roads to the resorts of Bílá and Bílý Kříž. Ostravice then creates a fresh water reservoir behind Šance Dam, for the industrial region around Ostrava finished in 1970. It has an area of 335 km2 (129 sq mi) and a 65 m (213 ft) high and 342 m (1,122 ft) long rockfill dam.