For decades, scientific research has shown that annual physical exams - and many of the screening tests that routinely accompany them - are in many ways pointless or [even] dangerous, because they can lead to unneeded procedures. The last few years have produced a steady stream of new evidence against the utility of popular tests. So why do Americans, nearly alone on the planet, remain so devoted to the ritual physical exam and to all of these tests, and why do so many doctors continue to provide them? Indeed, the last decade has seen a boom in what hospitals and health care companies call executive physicals" - batteries of screening exams for apparently healthy people, purporting to ferret out hidden disease. In 1979, a Canadian government task force officially recommended giving up the standard head-to-toe annual physical based on studies showing it to be "nonspecific," "inefficient" and "potentially harmful," replacing it instead with a small number of periodic screening tests, which depend in part on a patient's risk factors for illness. There is, of course, economic impetus for American medicine's "more is better" mode - at least when patients have insurance. In the United States, most doctors and hospitals profit more by doing more, and prices are particularly high for tests and scans. Also, we are one of the few countries where drug makers and hospitals advertise products and treatments directly to patients, creating demand from consumers who don't actually pay their full costs.