Two young men have denied allegations they took turns raping a girl behind a shed during an 18th birthday party in regional Victoria.

Mitchell Bowran and Charlie Star, both 22, faced the County Court on Wednesday, fighting multiple charges of rape dating back to a party in northeast Victoria in September 2017.

During his opening address to the jury, prosecutor Peter Triandos said the 17-year-old girl was raped as she repeatedly asked the men to stop.

But the men claim the sex was consensual and the girl was lying because of "concern about rumours and reputation".

Mr Bowran and Mr Star, 20 at the time, allegedly assaulted the girl after she kissed Mr Bowran.