While every service imaginable seems to have found a way to thrive on the Web, health has always lagged. But things are heating up, as an Internet billionaire is about to launch a site of his own and an online-health pioneer is changing its services to meet the challenge.

Steve Case, who brought the Internet into millions of homes and then ushered America Online through an ill-conceived merger with Time Warner, is wagering tens of millions of dollars that consumers will eventually pay about $100 a year to subscribe to premium services on his Web site. He believes that as Americans are forced to bear more of the cost of their health insurance they'll want a site that digitally stores their medical records and provides telephone services that coaches them about their health, matches them with doctors and helps them unsnarl insurance claims.

In launching RevolutionHealth.com Monday, Mr. Case says he aims to transform a "broken industry by putting health care back into the hands of the consumer." Skeptics, however, say his site -- which will start off free, but eventually begin charging for premium services -- may have trouble surviving, much less achieving Mr. Case's goal of remaking the health-care system.

Mr. Case faces not only the challenge of changing an industry that is both highly fragmented and deeply entrenched, but he also faces heightened competition right off the bat from the most-successful health site on the Internet. Also Monday, WebMD -- a company that nearly died more than once on its decadelong path to profitability -- announced a revamped site with new tools that match some of those offered by RevolutionHealth.com. WebMD users will now be able to personalize the site to a greater extent: storing and maintaining health records (which it will now make free), as well as joining forums specific to their health concerns.

"Health care is personal," says WebMD Health Corp.'s chief executive, Wayne Gattinella. "We're trying to give users a more relevant and accurate view."

Consumer-oriented health information is relatively scarce online. After WebMD and the site for the National Institutes of Health, the most popular health sites are general search engines -- Yahoo, MSN and About.com. A new site that launched in October, EverydayHealth.com, drew five million unique users in its first month. Its founders say they aim for the free site to be "WebMD-lite," providing simplified information, though it, too, will be revamped this year to offer more personalized services, such as forums and Web logs.

WebMD, which gets most of its revenue from ads, highlights the possibilities for health sites to pull in some of the $18 billion drug companies spend each year on promotions and educational efforts. The site floundered during the dot-com bust but survived to build its audience to 35 million unique users in the fourth quarter last year, and its stock price has nearly tripled, to $45 a share.

Mr. Case says he's undaunted by the competition. He began assembling Revolution LLC nearly three years ago, after resigning from AOL Time Warner. Revolution is pursuing businesses ranging from luxury condominiums to spas, but Mr. Case says health care is the "main event." He has put up $100 million of his own money.

Mr. Case says Revolution is stepping into the industry at an opportune time, when there's a growing push toward consumer-driven health care. A main idea behind Revolution is that Americans' health-care experience can be packaged under one brand.

But skeptics say consumers might not be ready for a one-stop shop. "They're talking about tying together a lot of different services, most of which no one has been very successful in developing," says Paul Ginsburg, president of the Center for Studying Health System Change, a Washington think tank.

Revolution will offer the standard elements of health-related Web sites free, such as disease information and articles and forums, but is hoping to break away from the pack through its paid telephone services.

In the past, WebMD has featured a few paid services, but as part of its relaunch, the site will now offer many of them free. "This is a market that can support multiple players," WebMD's Mr. Gattinella says. "We have a strong head start building an infrastructure and a team of 1,000 people who are focused on one thing alone -- health information."

Revolution Health Chief Executive John Pleasants says, "If they continue to innovate and raise the bar, it makes it tougher, but it'll make us better, it'll help us grow the category, and it justifies what we're doing."

It could be a risky proposition, given people's general reluctance to pay for Internet-based subscriber services. Revolution thinks that it can change this by drawing in users with a free trial: Users who sign up for RevolutionHealth.com within 90 days will get the telephone-consulting and digital-record services free for one year. The company says it eventually will charge under $100 a year.

Mr. Pleasants says the company envisions a day when users have online "health dashboards" that they use to manage their information, similar to the way people manage their finances online. For example, as part of its premium services, Revolution members will be able to download medical-expense software; on the free site, they'll be able to shop for health insurance, which the company believes will become more popular as employers increasingly move to a system of health-care-spending allowances for employees to purchase their own coverage.

Mr. Case says he sees RevolutionHealth as a "20-year journey" to have the impact he wants but aims for it to be profitable in three years. Mr. Case finds inspiration in the early days of AOL. "In 1985, no one believed people wanted interactive computer services," he says. "Most people thought we were crazy. Crazy ideas over time become mainstream."