Protests targeting Austria's right-wing Freedom Party (FPOe) in central Vienna have caused more than one million euros ($A1.5 million) in damages, police say.
Eleven police vehicles, as well as all the windows of a police station, were destroyed in the violence overnight on Friday.
Many shop windows in downtown Vienna were also smashed.
Police say 15 people were arrested and 20 injured in the demonstration that saw 6000 people protesting the FPOe's annual so-called Academics Ball, which was protected by 2000 police.
The protesters condemned the FPOe as a neo-fascist organisation, some comparing FPOe leader Heinz-Christian Strache to Anders Breivik, the Norwegian anti-immigration right-wing extremist who massacred 77 people in and around Oslo on July 22, 2011.