Cruise was quoted by Spanish magazine XL Semanal as saying he was diagnosed with the learning disability when he was 7 years old.
Cruise said he was often anxious, frustrated and bored as a youth and couldn't concentrate in class, the magazine reported on its Web site Sunday.
The magazine quoted Cruise as saying he was functionally illiterate when he graduated from school in 1980, but learned to read perfectly as an adult through Scientology technology.
XL Semanal said the interview was conducted in Los Angeles, but did not say when. A transcript of Cruise's original comments in English was not available.
The Church of Scientology was established in 1945 by science-fiction writer L. Ron Hubbard, and claims 10 million members around the world. Cruise and fellow actor John Travolta among its more famed followers.