The do-it-yourself movement is thriving at many local pharmacies. In addition to at-home pregnancy tests, you can buy kits to measure your cholesterol level and to diagnose urinary-tract infections and colon cancer. You can purchase devices to keep tabs on your blood pressure, blood-clotting time, and blood-glucose levels. And thanks to the Internet and walk-in labs, you can now order many of the same tests your doctor does.

In the best of circumstances, such home tests offer convenience, economy, and privacy—and they put the consumer in the driver's seat. Some can warn you of health dangers or offer reassurance that your vital signs are in order.

But not all home tests are accurate or easy to use. Even when they are, it often takes a medical professional's help to make sense of the results. "Home tests can help people become better partners in their health care," says Michele Curtis, M.D., associate professor of obstetrics and gynecology at the University of Texas Medical School in Houston. "But they should augment the health-care provider's role, not take its place."

This article first appeared in the November 2008 issue of Consumer Reports on Health.