Natalie Portman's taking it all off.

The actress, 29, is the new face of the Parfums Christian Dior line -- and in a new ad for Miss Dior Cherie, Portman appears topless, with her hands covering her chest.

Wearing just a black bow in her hair, the Black Swan star gives a sexy look over her shoulder.

The ad -- Portman's first cosmetics endorsement deal -- appears to have been shot prior to her announced pregnancy with fiance Benjamin Millepied's child.

But R-rated poses are nothing new to Portman, who played a stripper in Closer, had a raunchy love scene with Mila Kunis in Black Swan, and sexy encounters with Ashton Kutcher in No Strings Attached.