Some Burschenschaften are associated with right-wing or far-right ideas, in particular with the wish for a German state encompassing Austria.
Burschenschaften members identify which organisation they belong to by wearing coloured hats, and sashes around their chests.
Student Union representatives called for the Burschibummel and costumes to be banned from the university in October but University rector Heinz W. Engl said there was no legal basis for such a ban.
The Wednesday rallies will be held under the slogan "Burschis out of university and society!" The Union accuses the fraternity members of having "racist, extreme right-wing, homophobic and anti-Semitic ideas".
A group of socialist, green and communist student organisations will hold a demonstration on November 29th against the student fraternity WKR, which holds a controversial right-wing ball every January.