The Wendish question (Hungarian: Vendkérdés, Slovene: Vendsko vprašanje, Prekmurian: Vednsko pitanje, or Vendiško pitanje) in Hungarian politics concerns the origin and nomenclature of the Hungarian Slovenes.
The traditional Hungarian term for the Slovenes living in Hungary was "Wend" (Hungarian: vend). Many Slovenes in Hungary accepted this nomenclature, although in their dialect, they always referred to themselves as "Slovenes". In the last decades of the 19th century, and especially during the Horthy regime, the term "Wend" was used in order to emphasize the difference between the Slovenes of historic Hungary and other Slovenes.
The borders between Hungary and Serbia-Croatia-Slovenia were finally regulated by the Treaty of Trianon on June 4, 1920. The territory inhabited by the Slovenes (the so-called Vendvidék) was divided by the watershed of the two rivers Raba and Mura. The Mura region (Prekmurje in Slovene) including the areas of Murska Sobota and Lendava went to Slovenia, while the Raba Region (Porabje in Slovene) including nine communes around Szentgotthárd became part of Hungary. After this separation, the two regions developed independently in terms of economy, politics, culture and ethnicity.
After the German invasion of Yugoslavia in 1941, Hungary (re-)annexed the regions lost in 1920 including the Slovenian Prekmurje. It was expedient to argue that the inhabitants of the Prekmurje were not Slovenes after all, helping to substantiate Hungary's claim on the Prekmurje. Sándor Mikola (1871–1945), a well-known Hungarian physicist hailing from the Slovene Mura Region, used his influence to publicize this view in his book A Vendség múltja és jelene (The past and present of the Wends). In the book he describes how the Wends were descended from the Celts, but assimilated into the surrounding Slavic population. This theory has no scientific foundation and is not linguistically substantiated in the language of this population.
The Prekmurje remained a part of Yugoslavia (Slovenia) when the Trianon boundaries were restored after World War II.