SAN JOSE, Calif. — Five years ago, Barry Karlin sensed a huge business opportunity where most people saw only devastating social blight.

There were more than 16 million people in the United States who needed treatment for drug or alcohol addiction, but only one in five addicts who sought help could get it, because the number of programs was limited and the cost was so high.

Enter the Internet — or so Karlin imagined.

Rather than undergo the shame and awkwardness of face-to-face group counseling programs, addicts could find the support they needed in cyberspace. Karlin calculated the size of the potential market for drug treatment — online and off — at $12 billion.

Today, the company Karlin founded, CRC Health Group of Cupertino, Calif., is the country's largest provider of substance-abuse treatment, with 87 facilities in 21 states.

And CRC's eGetgoing program is the only accredited Internet-based addiction-treatment program in the United States.

The only thing missing is the addicts.

Even in the heart of Silicon Valley, where the pull of the Internet has proven strong enough to transform activities as diverse as driver's education and dating, the tug of methamphetamine, cocaine, heroin and alcohol is proving stronger than offers of cheap and confidential treatment. Since the program started in 2001, only about 1,000 addicts have logged on. Meanwhile, the company has continued to fill available slots at more traditional inpatient and outpatient programs.

"It's an entirely different mode of providing treatment," said Karlin, who says the main obstacle to the Web-based program's growth is that insurance companies are reluctant to pay for it.

Addicts receive group counseling from home, logging on twice a week for a one-hour session led by a counselor. The group communicates through headsets and microphones, using screen names of their choosing. There is streaming video of the counselor, but no photos or video of group members. Protecting privacy is paramount, Karlin said.

Still, the sense of community and trust can be very strong.

"I learned more from eGetgoing than I did in my entire life," said C.R. Watt, a woman who completed the program more than a year ago but has continued to attend an aftercare group hosted by the system.

Watt said the straight talk and support she found in her Internet group enabled her to change the way she thought about her life. "I had gone to AA places for so many years," she said. "There's no movement there."

The program costs $1,200 for 24 interactive sessions and a year of free aftercare sessions — compared with $3,000 or more for a typical 12-week outpatient drug-treatment program.

Like many mental health professionals, Robert Brooner, a medical psychologist at the Johns Hopkins Bayview Medical Center in southeast Baltimore, was initially skeptical about the benefit the Internet could bring to traditional psychotherapy. But Brooner said he recently tried eGetgoing and was surprised by its sophistication and ease of use.

Still, Brooner said, he is not surprised that droves of addicts aren't turning to the Internet for confidential counseling. Many have to be forced into face-to-face counseling.

"It's not that they don't want to go public," he said. "They are trying to persuade themselves that they are just using a little more than they did before and they will slow down. The disorder is designed to preserve and protect itself."

EGetgoing tries to address the stigma around addiction — and the hopelessness it can inspire — by defining drug dependence as a treatable medical condition.

"This is a chronic illness that requires management," said former U.S. drug czar Barry McCaffrey at a recent company event. "If we approach it from that perspective, we can absolutely get people into recovery."