What Is a DO? Doctor of Osteopathic Medicine Explained

If you’ve ever seen “D.O.” after a doctor’s name and wondered what it means, you’re not alone: more than 100,000 doctors of osteopathic medicine (DOs) now practice in the United States, representing one of the fastest-growing segments of the physician workforce. This guide separates fact from fiction, explains the training and philosophy behind osteopathic medicine, and helps you understand exactly what a DO can—and can’t—do for your health.

DOs in the US: Over 100,000 practicing doctors of osteopathic medicine ·
Osteopathic medical schools: 37 accredited colleges across the US ·
Share of US physicians: Approximately 11% of all doctors are DOs ·
Primary care proportion: More than half of DOs specialize in primary care ·
Year of founding: 1874 by Andrew Taylor Still

Here are the key facts about DOs in the United States.

What is a DO (Doctor of Osteopathic Medicine)?

What does a DO doctor do?

• A DO is a fully licensed physician who graduates from an osteopathic medical school. DOs use a whole-person, patient-centered approach to medicine (Cleveland Clinic (health system)).
• DOs receive additional training in osteopathic manipulative treatment (OMT) — a hands-on technique to diagnose and treat muscle, bone, and joint issues (Cleveland Clinic Health Essentials).
• The American Osteopathic Association recommends OMT for low back pain, stating it significantly reduces pain and improves functional status in patients with nonspecific acute and chronic low back pain (AOA (osteopathic professional organization)).

How is a DO trained?

• DOs complete four years of osteopathic medical school, followed by a residency program in their chosen specialty (Mayo Clinic (academic medical center)).
• They take the COMLEX-USA licensure exam, a three-level national standardized examination designed for osteopathic physicians (NBOME (osteopathic testing authority)).
• DO education includes 200+ hours of OMT instruction, emphasizing the relationship between structure and function (Cleveland Clinic (health system)).

The implication: For patients, choosing a DO means access to a physician who may incorporate hands-on techniques into a standard medical approach. The whole-person philosophy is a core tenet of osteopathic education, but whether it translates to measurably better outcomes remains an open question.

What is the difference between an MD and a DO?

Which degree is more respected?

• Both MDs and DOs are fully licensed physicians with similar training and practice rights. Respect depends on individual achievement rather than degree type (Mayo Clinic (academic medical center)).
• DOs emphasize holistic care and OMT; MDs follow an allopathic approach focused on diagnosing and treating specific symptoms (Cleveland Clinic (health system)).
• The key philosophical distinction often described for DO training is a whole-person, patient-centered approach emphasizing structure and function (Scripps Health (health system)).

Can DOs specialize in any field?

• Yes. DOs can enter residency, specialize, and practice across all medical fields, including surgery. They are not limited to primary care (Mayo Clinic (academic medical center)).
• The residency match system is now unified: the Accreditation Council for Graduate Medical Education (ACGME) accredits both DO and MD residencies, meaning DOs and MDs compete for the same positions (AOA (osteopathic professional organization)).

Six key differences, one pattern: DOs add OMT to conventional training, while MDs do not. But the table below shows the practical overlap.

The trade-off: DOs spend extra time learning OMT, which can reduce exposure to other specialties during medical school. But the single accreditation system has leveled the playing field for residency placement.

Why do doctors ask you to say “99”?

What is the purpose of saying ’99’ during a chest exam?

• Saying “99” helps a doctor assess lung sound transmission during auscultation — the vibration of the vocal cords changes the sound heard through a stethoscope, making it easier to detect abnormalities (Cleveland Clinic (health system) — DOs are trained in standard diagnostic procedures).
• This is a standard technique used by both MDs and DOs. It is not part of OMT.

Is this technique part of OMT?

• No. The “99” test is a conventional auscultation technique, independent of osteopathic manipulative treatment (Cleveland Clinic Health Essentials).
• OMT involves manual manipulation of the musculoskeletal system, not vocalizing specific words.

The catch: The “99” technique is so common that many patients assume it’s unique to DOs, but it’s simply a standard diagnostic tool used across all medical specialties.

What kind of patients do DOs treat?

Who should not see an osteopath?

• DOs treat patients of all ages and with any medical condition. Contraindications to OMT include fractures, infections, or certain vascular conditions such as deep vein thrombosis (PubMed (AOA guideline article)).
• DOs integrate OMT as part of comprehensive care, not as a replacement for conventional treatment. They can prescribe medications and perform surgery.

Can DOs treat chronic conditions?

• Yes. DOs are particularly common in primary care, where they manage chronic conditions like diabetes, hypertension, and arthritis. More than half of all DOs practice in primary care specialties (AOA (osteopathic professional organization)).
• A DO may use OMT to complement standard treatments for chronic pain, especially back pain, where the AOA recommends it as a first-line option (AOA (osteopathic professional organization)).

The implication: DOs are not niche specialists. They are primary care physicians, surgeons, and subspecialists who happen to have an extra tool in their kit. The only reason to avoid OMT is if you have a fracture, infection, or vascular condition that contraindicates manual manipulation.

What are the disadvantages of osteopathic medicine?

Is osteopathic medicine evidence-based?

• Some critics cite limited research on OMT efficacy compared to conventional treatments. While the AOA recommends OMT for low back pain, evidence for other conditions (e.g., asthma, headache) is less robust (PubMed (AOA guideline article)).
• The overall body of research on OMT is growing but still smaller than that for many pharmaceutical interventions.

Are DOs less competitive in residency?

• Residency placement differences have narrowed after the merger of allopathic and osteopathic match systems. In 2020, the ACGME became the single accrediting body, eliminating the separate AOA match (AOA (osteopathic professional organization)).
• DOs may face additional licensing steps in certain states or countries. For example, Pennsylvania requires osteopathic physician applicants to pass COMLEX-USA or an equivalent, and at least one year of approved post-graduate training (Pennsylvania Department of State (state licensing authority)).
• Some international medical boards do not recognize the DO degree, limiting practice abroad for osteopathic graduates.

The trade-off: For US patients, the disadvantages are minimal. The bigger concern is for international mobility or for those seeking highly specialized surgical fellowships where DOs historically had slightly lower match rates — though that gap is closing.

Is a DO a chiropractor?

How is OMT different from chiropractic adjustment?

• A DO is a physician licensed to practice medicine and surgery; a chiropractor is not. DOs can prescribe medications, order lab tests, and perform surgery (Cleveland Clinic (health system)).
• OMT focuses on the musculoskeletal system as part of whole-body diagnosis and treatment, whereas chiropractic primarily targets spinal subluxations (Cleveland Clinic Health Essentials).
• DOs undergo four years of medical school plus residency — a chiropractor typically completes a four-year doctoral program but is not a medical physician.

Are DOs considered real doctors?

• Yes. DOs are licensed physicians with the same professional rights and responsibilities as MDs. The Rhode Island law explicitly states that a license to practice osteopathic medicine confers the right to practice osteopathic medicine in all its branches as taught and practiced in accredited colleges (Rhode Island General Laws (state statute)).
• The Federation of State Medical Boards’ model practice act accepts either an MD or DO degree for licensure (Federation of State Medical Boards (national regulatory body)).

“DOs and MDs complete medical school and residency training, but DO education includes additional instruction in osteopathic manipulative medicine.”

— Mayo Clinic (academic medical center)

“Osteopathic manipulative treatment (OMT) is a hands-on technique used by some DOs to diagnose and treat muscle, bone, and joint issues.”

— Cleveland Clinic Health Essentials

“The American Osteopathic Association recommends OMT in the care of patients with low back pain.”

— American Osteopathic Association (professional organization)

For patients in the US, the choice between a DO and an MD is far less important than the individual doctor’s experience and bedside manner. The degree is a reflection of training philosophy, not quality of care. What matters is that the doctor is board-certified, takes your concerns seriously, and involves you in treatment decisions.

While both DOs and MDs are fully licensed physicians, understanding the key distinctions can help patients make informed choices, as explored in DO vs MD differences.

Frequently asked questions