Kostajnica

Kostajnica can refer to:

• Kostajnica, Bosnia and Herzegovina, 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