This is the oldest ball founded by a student fraternity. According to tradition, all the ladies at the ball who come alone or with a partner are supposed to wear a mask that covers their eyes and can invite someone to dance.

After midnight, women take their masks off, as in 'The Bat', Johann Strauss' operetta. This is the culmination of the evening which makes the Rudolfina Redoute a favourite among the Viennese.