What Is a Fellowship in Medicine?

The two get confused because fellows and residents work side by side and both hold an MD or a DO. The difference is the stage of training each one covers.

The length ranges come from the BLS, which says residencies run "from 3 to 9 years, depending on the specialty" and that "all states require physicians and surgeons to be licensed," which means completing residency. Board certification isn't required either, though the BLS says it "may increase their employment opportunities."

Fellows are often called by their postgraduate year. A doctor who finished a 3-year internal medicine residency and started a cardiology fellowship is a PGY-4. If those titles are new to you, the guide to resident doctors decodes intern, resident, fellow and attending.

A lot of them. The ACGME, which accredits US training programs, counted 167,083 residents and fellows in the 2024-2025 academic year. Of those, 29,651 (17.7 percent) were in subspecialty programs, which is mostly fellowship. There were 7,024 accredited subspecialty programs that year, more than the 5,380 specialty programs.

The share is highest in internal medicine. An analysis of NRMP data by Trilliant Health found that 64.5 percent of internal medicine residents pursued a subspecialty fellowship in 2025, up from 61.0 percent in 2018. So about 2 in 3 internal medicine residents are aiming past general internal medicine.

It depends on the subspecialty, and the certifying boards set the minimum. These lengths come from the American Board of Medical Specialties' requirements for subspecialty certification.

A few patterns stand out. Most pediatric subspecialties, like pediatric cardiology and neonatology, take 3 years. Most internal medicine subspecialties take 2, with cardiology and gastroenterology at 3. The 1-year fellowships, like sports medicine and hospice and palliative medicine, are open to graduates of several different residencies.

Some doctors stack fellowships. Interventional cardiology is a 1-year fellowship that requires certification in cardiovascular disease first, according to the ABMS. That path runs 3 years of internal medicine, 3 of cardiology and 1 of interventional cardiology, for 7 years of training after medical school. The timeline to becoming a doctor adds college and medical school to paths like this one.

You apply during residency, usually toward the end of it. Many fellowships fill through the NRMP's Specialties Matching Service, which works like the residency match: you interview, rank programs, programs rank you, and an algorithm pairs the lists. What happens on Match Day explains how that algorithm works for residency.

The biggest fellowship match is the NRMP's Medicine and Pediatric Specialties Match, which covers cardiology, gastroenterology, nephrology, the pediatric subspecialties and more. Its 2025 results came out December 3, 2025, for positions starting in the 2026 appointment year. That means you match months before your residency ends, so you plan for fellowship while you're still a resident.

That one match had 10,840 active applicants for 9,950 positions, and 78.7 percent of applicants matched. MD graduates matched at 89 percent (4,096 of 4,618), and DO graduates at 78 percent (1,351 of 1,728).

Across every match the NRMP runs for fellowships, the 2026 appointment year had 15,846 active applicants and 15,358 positions in 81 subspecialties. Of those positions, 12,963 were filled, a fill rate of 84.4 percent, and 81.8 percent of applicants matched.

The overall fill rate hides a wide spread. Some fellowships fill every slot, and others leave more than half empty. Here's what that looked like for six internal medicine subspecialties in the 2026 appointment year.

Some fellowships fill, some don't

Share of fellowship positions filled, 2026 appointment year

Cardiology filled all 1,347 of its positions, and gastroenterology and hematology-oncology each left 4 open. Geriatric medicine filled 151 of 388, under 40 percent. Nephrology and infectious disease also left more than a third of their spots open.

A full program suggests more applicants than spots. NRMP President Donna Lamb told the AMA that "the traditional thinking is that the lower those match rates are, the more competitive the subspecialty." She also cautioned that fill rates alone can't measure competitiveness, because the data don't show how many applicants of each type applied to each program.

Pay is part of the pull. The BLS puts the May 2025 median for cardiologists at $496,010, nearly double the $256,560 for general internal medicine physicians. Pay differences by specialty are covered in how much doctors make.

Yes, on the same stipend scale as residents, with raises for each postgraduate year. The AAMC's 2025 stipend survey, as reported by the AMA, gives these unweighted national averages:

A cardiology fellow who did 3 years of internal medicine trains as a PGY-4 through PGY-6. At those averages, the 3 fellowship years pay $244,144 in total.

Is that worth it? A rough estimate, before taxes and ignoring raises: a general internist who skipped fellowship would earn about $769,680 over the same 3 years at the BLS median ($256,560 times 3). That's $525,536 more than the fellow. After training, the cardiology median is $239,450 a year higher than the internal medicine median, so the fellow makes up that gap in a little over 2 years ($525,536 divided by $239,450 is about 2.2). The math tilts the other way for fields where the pay gap over general practice is small.

No. You choose a residency specialty during medical school, and the fellowship match happens during residency, so that choice comes later still. Nothing on your medical school application asks you to commit.

A few things help to know early, though:

• Your residency sets your options. Cardiology and gastroenterology run through internal medicine, and pediatric subspecialties run through pediatrics. If you're torn between primary care fields, the internal medicine vs family medicine comparison shows how the two differ.
• Fellowship adds years. A 3-year fellowship after a 3-year residency means 6 years of training after medical school instead of 3.
• Both degrees can do it. MD and DO graduates both match into fellowships, as the match numbers above show.

• Is a fellow a doctor? Yes. A fellow has an MD or a DO and has finished residency.
• Is a fellowship required? No. Residency is required for a license, and a fellowship is optional subspecialty training.
• How long is a fellowship? 1 to 3 years, per the BLS. Cardiology and gastroenterology take 3, nephrology takes 2, and geriatric medicine takes 1.
• What's the difference between a fellowship and a residency? Residency trains you in a specialty, like internal medicine. Fellowship comes after it and trains you in a narrower subspecialty, like cardiology.
• Do fellows get paid? Yes. The 2025 average was $77,593 for a PGY-4.
• How many fellowship positions are there? The NRMP's fellowship matches offered 15,358 positions for the 2026 appointment year.

All of this comes years after the MCAT^®. If you're studying now, the PurpleCAT concept library breaks the exam's science into short topics you can work through one at a time.

Last verified October 31, 2026, against the NRMP's 2026 Specialties Matching Service report, the ACGME's 2024-2025 statistics, the ABMS subspecialty certification requirements and the BLS Occupational Outlook Handbook. Fellowship lengths are board minimums; check individual programs for their exact terms.