Health care has long seemed one of the most local of all industries. Yet beneath the bandages, globalization is thriving.

The outsourcing of recordkeeping and the reading of X-rays is already a multibillion-dollar business.

The recruitment of doctors and nurses from the developing world by rich countries is also common, if controversial.

The next growth area for the industry is the flow of patients in the other direction -- known as "medical tourism" -- which is on the threshold of a dramatic boom.

Tens of millions of middle-class Americans are uninsured or underinsured and soaring health costs are pushing them and cost- conscious employers and insurers to look abroad for savings. At the same time the best hospitals in Asia and Latin America now rival or surpass many hospitals in the rich world for safety and quality.

On one estimate, Americans can save 85 percent by shopping around and the number who will travel for care is due to rocket from under 1 million last year to 10 million by 2012 -- by which time it will deprive American hospitals of some $160 billion of annual business.

The coming boom has its critics. Some worry that a flood of foreigners into developing countries will divert money and expertise from state health systems that are already overwhelmed -- an internal brain drain that will worsen care for ordinary people.

Others decry it as a distraction from the need to cut costs and improve quality in rich-world health systems.

But the private sector cannot be blamed for the failings of state-run health bureaucracies in developing countries, which neglected the poor long before medical tourists arrived. And the foreigners' arrival could improve things in developing countries, for the poor as well as the rich.