Horror writer Stephen King wrote an e-book
A survey by a British internet monitoring service, Envisional, has revealed that nearly 7,300 copyrighted books are available to download free.
It has discovered top titles are being "swapped on Napster-like file sharing systems and posted on the internet for free in their thousands".
Napster is an internet music-swapping service which drew angry accusations of copyright infringements from musicians and Envisional predicts that the publishing world is facing the same troubles.
A spokesman said: "The internet has enabled intellectual property theft - of the spoken word, still and moving images and music - on an almost unimaginable scale."
Top writers
Science fiction and fantasy titles have proved more common candidates for piracy.
Behind Stephen King in the league of top writers is Harry Potter author JK Rowling, Terry Pratchett, Tom Clancy and Douglas Adams.
Pirates use two methods of placing books on the web, which allow users to download and print out copies.
One is to scan text and then convert it into e-formulas.
A more complicated method is to "crack" copies of existing e-books such as King's novella Riding the Bullet.
This means getting hackers to disable the protection system around the file, allowing them to gain free access.
Clare Griffiths, a lawyer at intellectual property specialists Briffa, said: "Copying e-books and downloading them is a straight-forward copyright infringement by the pirate."
She suggested the easiest way of tackling the problems is to contact the internet service provider which hosts the illegal material.
There are also companies such as Envisional which protect intellectual property through security systems.