A Prahran bar has caused uproar after bouncers allegedly refused entry to a gay couple holding hands and told one woman accompanied by her girlfriend to 'put on a dress'.

Furious patrons have taken to restaurant review website Urban Spoon accusing bouncers at Hoo Haa Bar on Chapel Street of discriminating against gay couples.

One patron posted: "I am horrified that on Saturday night whilst eating dinner I overheard and witnessed a young lady be discriminated against for holding her gf hand whilst trying to enter the premises for dinner. I was so disgusted that I up and left."

Another patron claimed a bouncer refused entry to a woman holding her girlfriend's hand before advising her to go home and 'put on a dress'.

"Hoo Haa bar advised my beautiful, gay, neatly dressed, sober friend that she was not allowed in essentially because she was a lesbian. She was told to go home and put a dress on amongst other hateful comments as she showed up holding her girlfriend's hand."

Co-owner Paul Kasteel has flatly denied his business is discriminatory but said he would investigate the claims, posted to the website on July 12.

He told News Ltd: "As a business that's been operating for seven years, we've encouraged a diverse range of people to come to our venue.

"We've been a sponsor for the Melbourne Queer Film Festival for the last three years...we employ gay and straight people, we don't discriminate against staff, why would we discriminate against anyone else?"