Baarle-Hertog (Dutch pronunciation: [ˌbaːrlə ˈɦɛrtɔx]; French: Baerle-Duc, pronounced [baʁl(ə)dyk]) is a Flemish municipality of Belgium, much of which consists of a number of small Belgian enclaves fully surrounded by the Netherlands.

Four are linked to other Belgian municipalities, from west to east: the Baalbrugse Bemden, a strip of land along the Merkske, Zondereigen-Ginhoven and an area near Weelde-Station.

The largest single section, Zondereigen (named after its main hamlet), is located within mainland Belgium on the contiguous Dutch-Belgian border (north of the town of Merksplas).

During the First World War, this situation meant that the Imperial German Army could not occupy these parts of Belgium without crossing the Netherlands, which the Dutch government did not allow.

The Dutch government fenced off these areas and controlled access in or out of them, building a church and school for the Belgian people who were effectively stranded within the enclaves.

[6] In 2020, restrictions due to the COVID-19 pandemic differed between the two countries; for instance, preventing a Belgian citizen living metres away from an open Dutch bar from patronising it.