An M.D., or Doctor of Medicine, is a professional degree that qualifies someone to practice medicine in the United States and many other countries. It is the most common medical degree held by physicians in the U.S., earned after completing four years of undergraduate education, four years of medical school, and a minimum of three years of supervised residency training. From start to finish, becoming a practicing M.D. takes at least 11 years after high school.
What Medical School Looks Like
Medical school is a four-year program divided into two distinct phases. The first two years, known as the preclinical phase, focus on science training: how the body works, how diseases develop, how to diagnose and treat them. Students also learn foundational clinical skills like taking medical histories.
The final two years shift to clinical rotations (sometimes called clerkships), where students work directly with patients in hospitals and clinics under the supervision of experienced physicians. Rotations typically include internal medicine, family medicine, obstetrics and gynecology, pediatrics, psychiatry, and surgery, though the exact mix varies by school. This is where students discover which specialty fits them and begin functioning as part of a medical team.
Residency and Fellowship Training
Graduating from medical school doesn’t mean you can hang a shingle and start seeing patients on your own. Every M.D. must complete a residency, a period of intensive, supervised training in a chosen specialty. The length depends on the field. Internal medicine and pediatrics residencies run three years. General surgery takes five or more. During residency, physicians treat patients, make clinical decisions, and gradually take on more responsibility as they progress.
Some physicians pursue even further specialization through a fellowship after residency. A cardiologist, for example, first completes a three-year internal medicine residency and then adds two or three more years of cardiology fellowship training. This additional training is optional but required for many subspecialties.
Licensing Exams Along the Way
Earning the M.D. degree is only part of the equation. To legally practice medicine, physicians must pass the United States Medical Licensing Examination (USMLE), a three-step series spread across medical school and residency.
- Step 1 tests foundational science knowledge and is typically taken after the preclinical years.
- Step 2 CK (Clinical Knowledge) evaluates the ability to apply medical concepts to patient care, usually taken during the fourth year of medical school.
- Step 3 assesses readiness for unsupervised practice and is taken during residency.
Passing all three steps, along with completing residency, is required to obtain a full, unrestricted medical license in any U.S. state.
M.D. vs. D.O.
The other medical degree granted in the United States is the D.O., or Doctor of Osteopathic Medicine. Both degrees lead to full medical licensure, and both M.D.s and D.O.s can practice in any specialty, prescribe medications, and perform surgery. They take the same licensing exams and often train side by side in the same residency programs.
The key difference is in training philosophy. M.D. programs are referred to as allopathic medical schools, while D.O. programs are osteopathic. Osteopathic schools include additional training in osteopathic manipulative treatment, a hands-on approach to diagnosing and treating musculoskeletal issues. In day-to-day practice, the distinction between the two degrees has narrowed significantly, and patients can expect comparable care from either.
How International Graduates Earn U.S. Licensure
Physicians who earned their medical degree outside the United States or Canada follow a different path to practicing here. They must obtain certification from the Educational Commission for Foreign Medical Graduates (ECFMG), which verifies that their medical school meets international quality standards and that they’ve passed USMLE Step 1 and Step 2 CK. They also need to demonstrate English proficiency through an occupational English test.
Their medical school must appear in the World Directory of Medical Schools with an ECFMG notation confirming it meets eligibility requirements, and ECFMG independently verifies their diploma with the issuing school. Once certified, international graduates can apply to U.S. residency programs and, after completing residency and passing Step 3, qualify for a full medical license.
What M.D.s Earn
Physician compensation varies enormously by specialty. Based on data from recruiting firm AMN Healthcare covering engagements through early 2025, the average starting salary across all physician specialties was $403,000. But that number masks wide gaps. Family medicine physicians started around $275,000, while internal medicine averaged $292,000. On the surgical side, general surgeons averaged $419,000, urologists $521,000, and orthopedic surgeons $576,000.
These figures represent starting salaries for physicians entering practice after training. Compensation typically increases with experience, and factors like geographic location, practice setting, and whether a physician is employed by a hospital system or runs an independent practice all play significant roles.
Origins of the M.D. Degree
The M.D. has deep roots in American medicine. The first medical school in the country, the Medical College of Philadelphia (now part of the University of Pennsylvania), offered both a Bachelor of Medicine and a Doctor of Medicine degree in the 18th century. Earning the doctorate required holding the bachelor’s degree for at least three years, being at least 24 years old, and writing and publicly defending a thesis.
Modern medical education took shape largely because of the Flexner Report of 1910, a landmark evaluation of American medical schools commissioned by the Carnegie Foundation. The report was harshly critical of many institutions and led to widespread closures and reforms. Schools that emphasized laboratory instruction, dedicated teaching faculty, and hospital-based clinical training became the model. That framework, science-grounded classroom learning followed by hands-on clinical experience, remains the backbone of M.D. education today.