Google on Monday launched Google Health, a long-anticipated medical records service letting US users store and manage their health care information online.
The offering raises privacy concerns and draws yet another battle line between Internet search king Google and global software giant Microsoft, which began offering a similar HealthVault service in October.
"It isn't surprising both sides are going after it," Silicon Valley analyst Rob Enderle told AFP.
He said the service was likely to strongly appeal to "Baby Boomers" -- the generation of Americans born between the late 1940s and early 1960s.
"Health care is not just lucrative -- you are solving a problem critical to an aging group of Boomers. There are public relations and business benefits to it," he said.
Google said it built a secure computer platform separate from its search system to host medical records as part of an emphasis on keeping the health information protected.
"We have put in place the firmest privacy policy we can construct," Google vice president of search product and user experience Marissa Mayer told reporters at the Internet giant's headquarters in Mountain View, California.
"It is our highest level of security."
Privacy advocates however, seek proof that online medical information will be safe from tampering or snooping, possibly from insurance companies or employers out to reduce liabilities by shunning those with health issues.
"It's the Wild West online," said Deborah Peel, a psychiatrist who founded the nonprofit advocacy group PatientPrivacyRights.org. "The risks are massive."