Ursula K. Le Guin, the science fiction writer, was perusing the Web site Scribd last month when she came across digital copies of some books that seemed quite familiar to her. No wonder. She wrote them, including a free-for-the-taking copy of one of her most enduring novels, “The Left Hand of Darkness.”

Neither Ms. Le Guin nor her publisher had authorized the electronic editions. To Ms. Le Guin, it was a rude introduction to the quietly proliferating problem of digital piracy in the literary world. “I thought, who do these people think they are?” Ms. Le Guin said. “Why do they think they can violate my copyright and get away with it?”

This would all sound familiar to filmmakers and musicians who fought similar battles  with varying degrees of success  over the last decade. But to authors and their publishers in the age of Kindle, it’s new and frightening territory.

For a while now, determined readers have been able to sniff out errant digital copies of titles as varied as the “Harry Potter” series and best sellers by Stephen King and John Grisham. But some publishers say the problem has ballooned in recent months as an expanding appetite for e-books has spawned a bumper crop of pirated editions on Web sites like Scribd and Wattpad, and on file-sharing services like RapidShare and MediaFire.