A hospital fellowship is an advanced training program that doctors enter after completing residency to specialize in a narrow area of medicine. While residency trains a physician to practice independently in a broad field like internal medicine or surgery, a fellowship adds one to three years of focused training in a subspecialty like cardiology, allergy and immunology, or endocrinology. Fellows are fully licensed physicians who have already completed medical school and residency, making the fellowship the final stage of formal medical training.
How a Fellowship Differs From Residency
Residency and fellowship are both forms of graduate medical education, but they serve different purposes. Residency programs last three to seven years and give doctors broad clinical exposure across their chosen specialty. A surgical resident, for example, rotates through trauma, transplant, vascular, and other areas to build a wide foundation. Fellowship narrows that lens dramatically, training the doctor in one specific discipline within their specialty.
The practical difference shows up in daily work. Residents are transitioning from student to practicing physician, learning to manage patients across a range of conditions. Fellows handle more advanced and specialized cases, participate in complex procedures, and sometimes lead patient care teams. They have significantly more autonomy than residents because they’ve already completed years of supervised training, though they still work under attending physicians who serve as mentors.
What Fellows Actually Do
A fellow’s daily life revolves around their subspecialty. A cardiology fellow might spend mornings reading echocardiograms, afternoons in the catheterization lab, and evenings reviewing imaging for complex cases. The balance between clinical work, research, and teaching varies by program and subspecialty. Some fellowships are heavily procedural, while others focus more on diagnostic expertise or academic research.
Fellows take on greater responsibility for diagnosing and treating conditions that fall squarely within their subspecialty. They’re often the physician other doctors call when a case falls outside general practice. At the same time, they’re still learning. Fellowship training focuses on building the kind of clinical expertise that goes “over and above the competencies” developed during residency, as one study in BMC Medical Education put it. That means fellows are expected to refine judgment, not just accumulate knowledge.
Common Subspecialties That Require Fellowship
Nearly every major medical specialty has subspecialties accessible only through fellowship. In internal medicine alone, the list is long: cardiology, endocrinology, gastroenterology, pulmonology, infectious disease, rheumatology, nephrology, hematology, and oncology all require fellowship training. Surgery branches into subspecialties like surgical oncology, transplant surgery, and colorectal surgery. Pediatrics has its own parallel track with pediatric cardiology, neonatology, and pediatric emergency medicine, among others.
Within some subspecialties, there are even further levels of specialization. Cardiology is a good example. After completing a general cardiovascular diseases fellowship (typically three years), a cardiologist can pursue additional one- to two-year fellowships in interventional cardiology, electrophysiology, advanced heart failure and transplant, echocardiography, or vascular medicine. At Mayo Clinic alone, more than a dozen distinct cardiology fellowship tracks are available. This layered structure means some physicians spend well over a decade in training after college before they’re fully specialized.
How Long Fellowships Last
Most fellowships run one to three years. The exact length depends on the subspecialty. A general cardiovascular diseases fellowship is three years. Endocrinology, diabetes, and metabolism fellowships are typically two to three years. Allergy and immunology runs two to three years. Many highly focused programs, like echocardiography or preventive cardiology, last just one year.
To put the full timeline in perspective: a physician who decides to become an interventional cardiologist will complete four years of medical school, three years of internal medicine residency, three years of cardiovascular diseases fellowship, and then one to two additional years of interventional cardiology fellowship. That’s 11 to 12 years of training after earning a bachelor’s degree.
Fellowship Pay
Fellows are paid a stipend that’s higher than what residents earn but far less than what an attending physician makes. Pay is typically set on a graduated scale based on how many years a physician has been in training overall, not just in fellowship. At Mayo Clinic, for instance, stipends for the 2026 academic year range from roughly $75,000 at the first graduate level to about $106,000 at the tenth. A fellow entering after a three-year residency would land somewhere in the middle of that scale. This modest compensation relative to their experience level is one reason fellowship represents a significant financial commitment, especially for physicians carrying medical school debt.
Accreditation and Board Certification
Fellowship programs in the United States are accredited by the Accreditation Council for Graduate Medical Education, known as ACGME. The ACGME sets standards for training quality, supervision, and the clinical learning environment. These requirements ensure that fellows develop the skills and judgment necessary to take responsibility for complex patient care under the guidance of qualified faculty.
Completing an accredited fellowship is the pathway to subspecialty board certification. According to the American Board of Medical Specialties, physicians who want subspecialty certification must first be certified by their specialty board, then complete the required additional training and pass assessments of knowledge and clinical judgment in their subspecialty. Without completing a fellowship, a doctor cannot sit for these subspecialty board exams or market themselves as board-certified in that area.
Fellowships Beyond Physician Training
The term “fellowship” in a hospital setting doesn’t always refer to physician subspecialty training. Healthcare administration fellowships exist for professionals with master’s degrees in business administration, health administration, or related fields. These programs, typically one to two years, train early-career administrators to manage hospital operations, finances, and strategy. Mayo Clinic’s administrative fellowship program, for example, accepts candidates with MBAs and MHAs, as well as advanced practice providers like nurse practitioners and physician assistants.
Pharmacy fellowships, nursing fellowships, and research fellowships also exist at many academic medical centers, each designed to build advanced expertise within that discipline. When patients encounter a “fellow” in a hospital, though, the title most commonly refers to a physician in subspecialty training.