Schiffer, 37, a veteran of more than 500 magazine covers, wears a glossy black cat mask and covers her breasts with her hands on the magazine's cover above the word "sex" in giant red letters.
Inside in a photo essay titled "Claudia Schiffer: Revealed," the magazine juxtaposes a few sparse quotations about sex - such as "Eroticism means a force of attraction and results in a transfer of unbelievable energy" - with Testino's pictures of Schiffer cuddling a white Persian cat and coquetting on an office chair. In one shot she is draped in a wrap that appears to be made entirely of whole white rats.
The supermodel, known for her business sense and wholesome Teutonic beauty, said in a statement this week that Testino is "one of the few people I can completely trust - there are no boundaries at all when I'm shooting with him."
But despite a famous Citroën commercial in which she appeared naked - and was reportedly paid £3 million (€3.8 million) - in 1998, Schiffer has been reluctant in the past to appear nude in photo shoots.
She declined offers to pose in Playboy and is quoted on Vogue's website as saying, "It's not that I'm against nudity. I'm German, I'm very open, in Germany they lie in the park naked. It's just the principle."
She was widely quoted this week as telling Vanity Fair that she was a late bloomer: "Because I never read Bravo, I was 17 years old before I could even imagine sex."
Schiffer rose to prominence in the 1990s after being discovered in a disco in the northern German city of Düsseldorf at 17 years old. Her reign lasted through the decade, and she dabbled in acting before marrying film producer Matthew Vaughn in 2002. The couple has two children, born in 2003 and 2004.
One of a mid-1990s cadre of supermodels - including Elle MacPherson, Naomi Campbell and Cindy Crawford - who transcended their profession to become celebrities in their own right, Schiffer was known for cool management of her business empire. Forbes magazine reported that she made $9 million (€5.8 million) in 2001.
"Claudia goes out on the streets of Paris and something electrifying happens," Chanel designer Karl Lagerfeld told The New York Times in 1996, at the height of Schiffer's career as a supermodel. "But that doesn't explain her business success. Underneath she is all work, very serious, essentially a smooth-running German business machine."