Not coke. Not pot. Not smack.
We're talking about medications doctors prescribe to help them conquer learning disabilities such as hyperactivity and attention deficit disorder.
Last week, Cruise went to Washington to push one of the key causes of his Church of Scientology.
"There's a bill that just passed the House that makes it unlawful for schools and doctors to coerce children to get on drugs," he told us Thursday night at a benefit for MENTOR, the school charity that honored him for his work with tutoring programs. "We have some serious problems with education. I know a lot about it. There are 8 million kids that are being medicated with educational medication.
"Do you know about Ritalin, Adderall, psychotropic drugs?" Cruise went on. "When you break down the chemical compound, it's the same as cocaine. Bet you didn't know that."
We deferred to the "Minority Report" star, who has put his faith in the teachings of the late science fiction writer L. Ron Hubbard.
A few days before, Cruise, who has credited Scientology with helping him overcome dyslexia, lobbied for his position at a lunch with Education Secretary Rod Paige in Washington.
Cruise, who previously was a Bill Clinton supporter, may have been lobbying the White House for the funding of Scientology programs through President Bush's faith-based initiatives program, according to some familiar with the organization.
The actor, who took girlfriend Penelope Cruz to the MENTOR dinner, which was also attended by Tom Brokaw, Bill Russell, Libby Pataki, Lorraine Bracco and others, declined to say what he discussed with administration officials.
He did add, however, "I definitely promote religious tolerance everywhere."