Redford hosted his 25th annual festival in Park City, Utah, last month (JAN06), which was started in 1979 to showcase low-budget, independent films and talent.
However, as the festival grows larger and larger every year, some celebrities have begun turning up just for parties, even though they have nothing to do with the films on show.
Redford tells Newsweek magazine, "To the outside world, it's a big fat market where you have people like Paris Hilton going to parties. Now, she doesn't have anything to do with anything.
"I think the festival is close to being out of control."
Despite Redford's disdain for the socialite, Hilton has attended the parties of Sundance every year since 2004.