We're not quite sure who started the rumours...
But apparently people are under the impression that Scarlett Johannson is a bit of a minx.
And she wants to put the record straight.
The Black Dahlia actress, who is currently dating her co-star Josh Hartnett, insists she is a taken woman, although she does admit to, erm, enjoying herself when she has been young, free and single.
She told US magazine Allure: "Contrary to popular belief, I'm not promiscuous.
"There does seem to be a mistaken belief out there that I am sexually available somehow - which is not to say that I'm not open-minded about sex... yet I wouldn't say I'm a serial monogamist, either.
"I mean, I went through periods of time when I was, ah, single. But when I'm in a relationship, I'm in a relationship."
Having said that, Scarlett believes monogamy may not be a natural thing for human beings.
She said: "I do think on some basic level we are animals, and by instinct we kind of breed accordingly.
"But as much as I believe that, I work really hard when I'm in a relationship to make it work in a monogamous way."
The actress went on to say that she gets HIV tested twice a year and screened for sexually transmitted diseases, adding that it's "irresponsible" for people not to.
Social bookmarking allows you to save and categorise a personal collection of bookmarks and share them with others. This is different to using your own browser bookmarks which are available within your web browser.
Use the links on the left to share this page on the social bookmarking site of your choice.
Read more about social bookmarking at: Wikipedia - Social Bookmarking