The Internal Western Outland Revolutionary Organisation (bulg. Вътрешна западнопокрайненска революционна организация), IWORO, was a Bulgarian revolutionary organisation active in the Western Outlands in Serbia between 1921 and 1941.

The organisation was established in 1921 on the basis of several detachments created straight after the cession of the Western Outlands to Serbia in 1920. The IWORO initially concentrated on propaganda and delivery of Bulgarian literature. The period of armed resistance started in 1922 and the organisation carried out numerous assaults on the Tzaribrod–Belgrade railway, on bridges, Serbian garrisons and barracks until 1941 when the region was occupied by Bulgarian troops.

Unlike the other three Bulgarian revolutionary organisations active in the interwar period — the Internal Macedonian Revolutionary Organisation in Macedonia, the Internal Thracian Revolutionary Organisation in Thrace and the Internal Dobrujan Revolutionary Organisation in Dobruja — IWORO did not put up the tactical slogan demanding autonomy for the region but fought “for the liberation of the Western Outlands and their restoration to Bulgaria”.

See also

• Western Outlands