(Photo by Tim Dillon, USA TODAY)

Paying for travel guides soon could be a thing of the past.

In a move publishers are watching closely, the fast-growing Rough Guides series is putting its entire line of 103 books on the World Wide Web for free, starting Tuesday.

Would-be vacationers will be able to read the books from front to back or search for a specific topic. They'll also be able to print out copies.

"We see it as the next logical step" as people increasingly use the Web instead of guidebooks to plan trips, says Rough Guides' SoRelle Braun, noting that the line tested the concept with a handful of books three years ago.

Braun says the company expects to make its money by selling advertising at the Web site, where it expects a surge of traffic, and by licensing the text to other travel Web sites. But it also expects regular book sales to continue for now.

While travelers are using the Internet more to plan where to go, they "still want that real book, with the color maps and photos, in their hand" to take with them, Braun says.

Giving away its books on the Web will, if anything, help sell more copies by making the brand better known, Braun says. But other publishers aren't so sure the concept is a good idea. "Our core market remains books sold through bookstores, and there's tremendous concern that giving away the text on the Internet can cannibalize that," says Greg Cohn, who oversees Let's Go, the largest budget guide series.

Cohn says Let's Go plans to beef up its Web site in September but will stop short of putting entire books on line. "We want (our Web site) to be a resource to travelers, but we don't want to give away the store."

Travel guide publishers are facing a "dilemma" as the number of people using the Web to plan trips soars, says Brent Peich, head of Fodor's Web site.

Travelers will gravitate to the sites that have the most information. And those sites could end up dominating travel information in the future. But, like Cohn, Peich fears that offering too much over the Web could eat away at book sales.

Fodor's, the largest travel book publisher with 290 titles, did extensive studies on whether to put all its books on line before deciding to hold off for now, he says. Instead, it has about 25% of its 80-book Gold Guide series available.

But Peich says they're keeping a close eye on Rough Guides. "God bless them if they can make it work. I'll be right on their tail if they can."

Rough Guides' books won't all be available at once. Five titles (Europe, USA, New York, San Francisco and England) will appear at its site (www.roughguides.com/travel ) Tuesday, and more will be added every few weeks. All 103 should be on line within 18 months.