The Gleichbehandlungskommission said it was constantly having to deal with complaints that prices and promotions were dependent on gender - with men saying they were never the ones to benefit from such offers financially.
The Ombud has now issued a report condemning Ladies' Nights promotions and saying that they violate the Equal Treatment Act - which paves the way for men to sue a nightclub for damages if they believe they have been discriminated against.
"All goods and services offered in the context of commercial activities should be priced regardless of gender," the report said. It added that events could be marketed as gender-specific but that any goods on offer must be priced the same for men and women.
Bars and clubs have argued that Ladies' Nights are meant to compensate women for the fact that they generally earn less than men, but the Ombud said this was not relevant.
Equal rights lawyer Ines Grabner-Drews said that "it is unlikely that companies in the entertainment and leisure sector are really concerned about equal pay” and that the real motivation behind Ladies' Nights is to attract more women to nightclubs, which helps draw in more men.
Cineplexx cinemas in Austria regularly hold Ladies' Nights - offering a special €8.30 ticket for a romantic movie which includes a small bottle of Martini Asti and sweets, but the small print makes it clear that men can also benefit from the offer.
Vienna's popular U4 nightclub had a ‘Girls Special' night until recently, when women got into the club for free, but U4 spokeswoman Lisa Schwarzinger said this was likely to be discontinued. “Of course we can't be seen to be favouring women with free entry,” she said.
Some restaurants have also had Ladies' Nights promotions, where female diners are offered a free drink and dessert with their meal.
However, women don't always get the better deal - especially when it comes to services such as hairdressing. A court in Denmark recently ruled that Danish hair stylists can continue to charge different prices for men and women and that gender-based pricing is not discriminatory.