Kotor-Varoš was a srez (a second-level administrative unit) centered at Kotor Varoš, that existed during the Kingdom of Yugoslavia and Socialist Yugoslavia. It had earlier been a kreis of Austro-Hungarian Bosnia and Herzegovina. It was a subdivision of the Vrbas Oblast in 1922–29, Vrbas Banovina in 1929–41, and thereafter the Socialist Republic of Bosnia and Herzegovina. It was abolished in 1955.[1]
In 1948[2] and 1953, it included the six municipalities of Kotor Varoš, Previle, Skender Vakuf, Šiprage, Vrbanjci and Zabrđe.
| Census area | Total | Serbs | Croats | Slovenians | Macedonians | Montenegrins | Yugoslavs undecided | Czechs | Poles | Rusyns –Ukrainians | Other Slavs | Other non-Slavs |
| KOTOR VAROŠ COUNTY | 37898 | 25008 | 6485 | 4 | 4 | 10 | 6375 | 2 | – | 2 | – | 8 |
| Kotor Varoš | 4715 | 805 | 2640 | 2 | 3 | 6 | 1253 | 1 | – | 1 | – | 4 |
| Maslovare | 4574 | 3966 | 8 | – | – | – | 600 | – | – | – | – | – |
| Preville | 4576 | 3537 | 696 | – | – | – | 342 | – | – | – | – | 1 |
| Skender Vakuf | 7100 | 6566 | 16 | – | – | – | 518 | – | – | – | – | – |
| Šiprage | 7746 | 6036 | 24 | 1 | 1 | – | 1682 | – | – | – | – | 2 |
| Vrbanjci | 4919 | 1678 | 1728 | 1 | – | 4 | 1505 | 1 | – | 1 | – | 1 |
| Zabrđe | 4268 | 2420 | 1373 | – | – | – | 475 | – | – | – | – | – |