Kostajnica

Kostajnica can refer to:


 * Kostajnica, Bosnia and Herzegovina (formerly Bosanska Kostajnica), a town on the right bank of river Una, in Bosnia
 * Hrvatska Kostajnica, a town on the left bank of river Una, in Croatia
 * Kostajnica, Doboj, a village near Doboj, Bosnia and Herzegovina
 * Kostajnica, Konjic, a village near Konjic, Bosnia and Herzegovina