Austria (1,548 km2) Vas (Latin: Comitatus Castrifèrreus, German: Eisenburg, Slovene: Železna županija or Železna) was an administrative county (comitatus) of the Kingdom of Hungary.

Vas County arose as one of the first comitatuses of the Kingdom of Hungary.

The former Yugoslavian part of the county was occupied and annexed by Hungary between 1941 and 1945 during World War II.

In 1919 there was briefly proclaimed Republic of Prekmurje, but it existed only a few days, alike the Lajtabánság.

In 1900, the county had a population of 418,905 people and was composed of the following linguistic communities:[1] Total: According to the census of 1900, the county was composed of the following religious communities:[2] Total: In 1910, the county had a population of 435,793 people and was composed of the following linguistic communities:[3] Total: According to the census of 1910, the county was composed of the following religious communities:[4] Total: In the early 20th century, the subdivisions of Vas county were: The towns of Oberwart and Güssing are now in Austria; Murska Sobota is now in Slovenia.