The Alliance led a campaign focused on the legacy of Joerg Haider in Carinthia
Austrian far-right parties have made gains at the cost of the governing Social Democrats in two regional polls.
In Carinthia, the main winner was the Alliance for the Future of Austria of the late Joerg Haider, with 45.5%. The Social Democrats trailed with 28.6%.
The centre-left Social Democrats also lost ground in Salzburg, but still came first with 39.5%. The far-right Freedom Party won 13% there.
The far-right gained nearly 29% of the vote in September's general election.
However, neither the Alliance nor the Freedom Party were invited to join the reconstituted coalition government formed two months later by the Social Democrats and the conservative People's Party.
Sunday's regional elections in Salzburg and Carinthia were the first to put to the test the popularity of the government, which has focused in recent months on dealing with the problems confronting Austria in the face of the global economic downturn.
Correspondents say that in Carinthia the Alliance had led a campaign focused on the legacy of Haider, who was the state's governor for 10 years.
"We will look after your Carinthia," the party's posters said.
Haider was killed in a high-speed car crash near Klagenfurt last October. His blood-alcohol level had been well above the legal limit.
He became a potent force in the 1980s and 90s, championing what he called traditional family values and an end to immigration.