The 59-year-old star used paper towels to boost her bust and win roles early on in her career when she was auditioning for theatre roles in New York.
She said: "I have cheated to get a part. The first time was on Broadway years ago. Before the audition I filled my 32DD bra cups with paper towels. I got the part!
"I did it again to Sydney Pollack for Out of Africa. I'd heard he didn't think I was sexy enough so I filled them up again."
The Oscar-winning actress - who has four children with her husband, sculptor Don Gummer - previously revealed she thinks women have to wear make-up to be successful in life.
Meryl took a risk by ditching her usual beauty regime to play a stern nun in her Oscar nominated movie Doubt, in which she stars alongside Philip Seymour-Hoffman.
She said: "The really freeing thing about playing the role was that you throw away everything that woman normally waste a great number of hours of the day on - what you're going to wear, how your hair looks, how your face is.
"Everything is gone and all you have is what you do. It's kind of the way we should be, you know, instead of wasting a lot of time on the things that get you ahead in the world - because they do."