Catarina Migliorini, a physical education student of Italian descent, has till now been offered $155,000.
She hopes to pump in the money into a non-governmental organisation that will construct houses in the southern Brazilian state of Santa Catarina.
The girl rejected claims that she was a prostitute, and said she still believed in love, the daily reported.
She will reportedly be followed every step of the way by an Australian film crew for a documentary called "Virgins Wanted".
"I saw this as a business. I have the opportunity to travel, to be part of a movie and get a bonus with it," the woman said.
"The auction is just business, I'm a romantic girl at heart and believe in love. But this will make a big difference to my area," she said.
Catarina signed up to the project two years ago when she saw an advert by Thomas William Productions looking for a virgin to film.
Director Justin Sisely will "record her emotions" before and after her first sexual encounter. A male virgin called Alexander is also being followed.
She will get $20,000 and 90 percent of the final auction sale price, which ends Oct 15.
The winner will be tested for sexually transmitted diseases prior to the encounter that will take place on a plane, leaving Australia for the US.
London: A 20-year-old Brazilian woman student is auctioning off her virginity to the highest bidder to raise cash to build homes for poverty-stricken families, the Daily Mail reported.
First Published: Friday, September 28, 2012, 20:19