US film studios and cinemas are teaming up to launch an ad campaign to deter people from copying and swapping movies on the internet.
George Lucas appears in the ads
Members of the industry from cinema workers to Star Wars director George Lucas will feature in the advertisements, to be screened in cinemas across the country.
They will warn that swapping films online could endanger a business which employs tens of thousands of people.
While US cinemas took $9.5 billion (£5.9bn) in revenues last year - the highest since 1957 - industry executives fear a huge jump in the number of films being copied.
In the advertisement, Lucas warns: "If people keep taking for free, it will cease to exist. It's as simple as that."
The Motion Picture Association of America (MPAA), which represents the major studios, estimates between 400,000 and 600,000 films are downloaded every day.
The music industry has complained that file-swapping is leading to a slump in CD sales.
While slower dial-up connections have meant Hollywood has avoided the same fate, improved technology and faster broadband connections now mean more PC users have the storage space and the capability to download movies.
Improved technology means a bigger threat to Hollywood studios
"Piracy is the single most pressing issue facing our industry," Fox Filmed Entertainment chairman Jim Gianopulos said at the ShoWest cinema trade convention.
He added that while the movie industry has faced many challenges over the past century, "what we can't compete with is free".
Older forms of piracy are still costing the industry dear.
People sneaking handheld video cameras into cinemas and projection booths, then copying the results - or making bootleg copies of promotional DVDs - costs the industry $3bn (£1.9bn) each year, said the MPAA.
The trade group has put aside $150,000 to reward informers whose tips led to raids on DVD factories in Asia.
Of the seven million pirated DVDs seized globally, it said 6.1 million of them come from the continent - costing it $642m (£400m)
Losses from China alone are estimated at $168m (£105m), while piracy in Japan is said to cost
The National Copyright Administration of China's deputy director general, Wang Ziqiang, told the conference his country's government was "determined to protect the rights of copyright holders and determined to fight piracy".
The drive to end piracy is being backed up by an advertising campaign in India, Indonesia, South Korea, Malaysia, Singapore, Taiwan, Thailand and the Philippines.
It will use the slogan: "Nothing Beats The Real
Thing: Say 'No' To Piracy."