Piracy in China cost the film industry $2.7bn (£1.5bn) in 2005, according to a study by a major global movie body.
Pirated DVDs can hit the streets days after a film is released
Around 93% of all films sold in China are pirated, the Motion Picture Association (MPA) study said.
The Chinese film industry was worst affected, losing around $1.5bn (£812m) to piracy, it said, while major US film studios lost around $565m (£306m).
According to the MPA report, almost 40% of the losses come from people downloading films on the internet.
"In terms of who's losing the most here in China, it's not the MPA's member companies, it's the local industry," MPA Asia Pacific head Mike Ellis said.
But the losses to US studios in China have risen since 2003, when the MPA estimated that film companies lost $168m (£91m).
European and US firms have long complained about the volume of pirated goods on sale in China.
The MPA is also frustrated at its lack of access to the Chinese market.
Only 20 foreign films are allowed into the country each year, it says - and even those face restrictions on their runs.
A separate study commissioned by the MPA showed the number of people going to see films in China went up by 30% last year, with ticket sales worth $247m (£134m).
But growth in China's box office is slowing, it said.
The MPA is the international counterpart of the Motion Picture Association of America, which represents the interests of the major Hollywood film studios.