Grand Duchy of Slovakia
Veľkovojvodstvo Slovenska (sk)
Großherzogtum Slowakei (de)
Component of Greater Austria
Flag of First Slovak Republic 1939-1945.png Slovakia by soaringaven.png
Flag Coat of arms
Nad Tatrou sa blýska
Slovakia 1918 by SoaringAven.png
The Slovak Grand Duchy after its proclamation in 1918
Capital Bratislava
Languages Slovak, German, Hungarian
Government Constitutional monarchy, personal union with the House of Habsburg
Grand Duke
 •  1918–1922 Karol I
 • 1922–1941 Otto I
Prime Minister
 • 1918–1928 Andrej Hlinka (first)
 • 1939–1941 Vojtech Tuka (last)
Historical era Interwar period
 •  Grand Duchy proclaimed 29 October 1918
 • 1918 Imperial Manifesto 16 October 1918
 • National Uprising 29 August 1941
 •  Dissolution of Greater Austria 13 March 1941
Currency Schilling (S)
Preceded by
Succeeded by
Flag of Hungary (1867-1918).svg Lands of the Crown of Saint Stephen
First Czechoslovak Republic Flag of Czechoslovakia.svg
Today part of Flag of Czechoslovakia Czechoslovakia

The Grand Duchy of Slovakia (Slovak: Veľkovojvodstvo Slovenska) otherwise known as the Slovak State (Slovak: Slovenský štát) was a autonomous state within the United States of Greater Austria which existed between 29 October 1918 and 13 March 1941. It controlled the majority of the territory of present-day Slovakia, but without its current southern and eastern parts, which then formed part of Hungary. The grand duchy bordered Galicia, Bohemia and Moravia, German-Austria and Hungary.

It is consider the first Slovak state by modern historians. Proclaiming independence from the Kingdom of Hungary as an equal component of the Austro-Hungarian Empire on 29 October 1918. When Emperor Karl I recognised the state the following day, Hungary terminated its union with Austria on 31 October.

With the dissolution of Greater Austria following World War II, the Slovak lands merged with Bohemia and Moravia to form Czechoslovakia.