An MD is a Doctor of Medicine, the most common medical degree held by physicians in the United States. It’s an allopathic medical degree, meaning it’s rooted in diagnosing and treating diseases using evidence-based interventions like medication, surgery, and other therapies. Of the more than 1 million active physicians in the U.S. as of 2024, the vast majority hold an MD degree.
What MD Training Looks Like
Becoming an MD requires a minimum of 11 years of education and training after high school, and often more. The path starts with a four-year undergraduate degree. There’s no required major, but students must complete prerequisite coursework in biology, chemistry, physics, and other sciences. During college, students take the Medical College Admission Test (MCAT), typically in the spring of their junior year, and submit medical school applications the following summer.
Medical school itself lasts four years. The first two years focus on foundational sciences: anatomy, pharmacology, pathology, and how the body works at a cellular and systems level. The final two years shift to clinical rotations, where students work directly with patients in hospitals and clinics across specialties like surgery, internal medicine, pediatrics, and psychiatry. After completing medical school, graduates earn the MD degree but aren’t yet ready to practice independently.
Residency and Specialization
Every MD must complete a residency, a period of supervised, hands-on training in a specific specialty. Residency length varies widely depending on the field:
- Family medicine, internal medicine, or pediatrics: 3 years
- Psychiatry or obstetrics/gynecology: 4 years
- General surgery, orthopedic surgery, or urology: 5 years
- Plastic surgery: 6 years
- Neurosurgery: 7 years
Some physicians pursue additional fellowship training after residency to subspecialize further, adding one to three more years. A cardiologist, for example, first completes a three-year internal medicine residency, then a cardiology fellowship. By the time some specialists finish training, they may be in their mid-30s.
Licensing and Board Certification
To practice medicine legally, every MD must pass the United States Medical Licensing Examination (USMLE), a three-part series taken at different stages of training. Step 1 tests foundational science knowledge. Step 2 evaluates clinical knowledge and the ability to apply it to patient care. Step 3, taken during or after residency, assesses readiness for unsupervised practice. Passing all three steps is required for a state medical license.
Licensing and board certification are two different things. A license permits you to practice medicine. Board certification is a voluntary credential that signals deeper expertise in a specialty. The American Board of Medical Specialties oversees 24 member boards that certify physicians across 40 specialties and 89 subspecialties. To become board certified, a physician must complete residency training, pass a specialty-specific exam, and commit to ongoing education throughout their career. Most hospitals and insurance networks prefer or require board certification.
How MDs Differ From DOs
The other medical degree in the U.S. is the DO, or Doctor of Osteopathic Medicine. In practice, MDs and DOs are far more alike than different. Both complete four years of medical school, train in residencies, pass licensing exams, prescribe medications, perform surgery, and practice in every specialty. They often use the same textbooks and take the same courses.
The key distinction is in training philosophy and one additional skill set. DO programs include training in osteopathic manipulative treatment (OMT), a set of hands-on techniques involving stretching, gentle pressure, and resistance applied to muscles and joints. This gives DO students extra focus on the musculoskeletal system. Osteopathic programs have historically described their approach as more holistic, emphasizing the connection between mind, body, and spirit. In day-to-day patient care, though, an MD and a DO in the same specialty provide essentially the same quality and type of treatment.
International Medical Graduates
Doctors who earned their medical degree outside the United States can also practice in the U.S., but the path is more complex. They’re classified as international medical graduates (IMGs) and must obtain certification from the Educational Commission for Foreign Medical Graduates (ECFMG). This process requires that their medical school be listed in the World Directory of Medical Schools, that their diploma be verified directly with the issuing school, and that they pass the same USMLE steps as U.S.-trained physicians. IMGs must also match into and complete an accredited residency program before they can obtain a full, unrestricted medical license.
What MDs Actually Do
As of 2024, the U.S. had about 1,032,000 active physicians, with roughly 866,000 of them providing direct patient care. That works out to about 255 patient-care physicians per 100,000 people. MDs work in nearly every corner of healthcare: primary care offices, emergency departments, operating rooms, psychiatric clinics, research labs, and public health agencies. Some MDs never see patients at all, working instead in medical research, pharmaceutical development, health policy, or hospital administration.
The scope of what an MD can do is the broadest of any healthcare provider. With appropriate training, MDs are licensed to diagnose conditions, prescribe any medication, perform surgery, order and interpret diagnostic tests, and manage complex, multi-system diseases. Their specific day-to-day work depends entirely on the specialty they chose during residency. A dermatologist’s Tuesday looks nothing like a trauma surgeon’s, but both followed the same foundational path to get there.