Q. I go to a group of physicians that has both MDs and DOs practicing in it. What is the difference between a Medical Doctor and a Doctor of Osteopathy? How is their training different? What are they each capable of doing in practice?

A. Although there were more differences between MDs and DOs earlier this century, today DOs and MDs have much more in common than not. In fact, many people may see a physician and not even realize that they're seeing a DO rather than an MD. MDs and DOs are the only two types of physicians licensed to practice medicine and surgery in the United States.

MD physicians are traditional medical doctors. They are sometimes also referred to as allopathic physicians. Doctors of osteopathy are also known as osteopaths or DOs.

Osteopathy is a school of medicine that began as an outgrowth of conventional medicine in the latter part of the 19th century. Its original emphasis was on preventive medicine and on helping the body to heal itself. Osteopathy also focused on the musculoskeletal system--the connections among nerves, muscles and bones.

One notable way in which osteopathy differs from traditional medicine is in its use of osteopathic manipulative treatment, or OMT. Osteopaths use this hands-on technique to diagnose and treat medical problems. In this regard, it's similar to chiropractic.

Unlike chiropractors, however, osteopaths receive training that is nearly identical to that of medical doctors. Osteopaths and MDs typically complete four years of college as undergraduates, then go on to four years of medical training. They take similar courses on anatomy, pathology and pharmacology.

Both groups also spend blocks of time in hospitals working in various medical fields including obstetrics and surgery. They then enter residency training in the same types of specialties, such as internal medicine, family practice, pediatrics, obstetrics, psychiatry or surgery. DOs and MDs must pass comparable state licensing examinations.

DOs are more likely than MDs to emphasize primary care in their training and practice. They tend to practice "whole person" medicine, rather than specializing in one area. Some DOs do, however, go on to specialize in areas such as heart surgery, radiology, neurology and gastroenterology.

There are about 45,000 osteopaths in the United States, accounting for about 5 percent of the total U.S. physician population. Many DOs practice in small towns or rural areas, and they are more common in the Midwest and West.

For more information, contact the American Osteopathic Association at 142 E. Ontario St., Chicago, IL 60611; the group's telephone number is 1-800-621-1773 and its Web site address is http://www.am-osteo-assn.org.

Jay Siwek, chairman of the department of family medicine at Georgetown University Medical Center, practices at the Fort Lincoln Family Medicine Center and Providence Hospital in Northeast Washington.

Consultation is a health education column and is not a substitute for medical advice from your physician. Send questions to Consultation, Health Section, The Washington Post, 1150 15th St. NW, Washington, DC 20071. Questions cannot be answered personally.