Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android

About Andrew Karaba

Andrew Karaba is a fellow in infectious diseases at Johns Hopkins University. He completed his MD and PhD at Northwestern University, where his thesis research focused on herpes simplex virus pathogenesis. Following completion of the Medical Scientist Training Program, he finished a residency in internal medicine through the Osler Medicine Training Program at The Johns Hopkins Hospital.


After spending 10 or more years getting an MD, a PhD, and completing residency, you may feel you are finally ready to live the physician-scientist dream and start a lab while spending a portion of your time doing clinical work. However, many MD-PhDs complete one final step in their medical and scientific training before launching their career. This period of training is referred to as fellowship. Fellowship is a time to refine your clinical interests in a subspecialty (such as gastroenterology, pediatric nephrology, cardiac anesthesia, or dermatopathology) and sharpen your research skills before you are truly on your own. This chapter will describe fellowship, important considerations in choosing a fellowship for MD-PhDs, how to make the most of your fellowship, and briefly describe what comes next.

What Is a Fellowship?

A fellowship is a period of training after residency that can last as little as 1 year and as long as 5 years depending on your specialty, the specific fellowship program, and your goals. Nearly all fields of medicine have subspecialties. Urogynecology is a subspecialty of gynecology, rheumatology is a subspecialty of both internal medicine and pediatrics, and colorectal surgery is a subspecialty of general surgery. The list of all subspecialties is quite extensive. The purpose of the fellowship is twofold: to gain additional clinical skills necessary to be a subspecialist and to pursue scholarly activities. Most fellowships have both clinical and research periods to accomplish these goals. The clinical portion is similar to residency in that a fellow will see and treat patients under the supervision of a more senior attending physician. The research portion can take many forms. It can look very much like a traditional postdoctoral fellowship in which the fellow is working in the lab of a senior scientist (principal investigator or PI). However, some fellows pursue more clinically focused projects in which they spend their research time acquiring additional analytical skills in order to do clinical research under the guidance of their mentor. The process of applying to a fellowship begins in residency.


  • Fellowship provides subspecialty clinical training as well as research training.

  • Most MD-PhDs complete a fellowship, but this is specialty-dependent and may not be necessary to have a career as a physician-scientist.

  • Research might be combined with residency if you pursue a research pathway.

  • Choosing a fellowship mentor is a critical decision.

  • When choosing a fellowship program, select one whose graduates have the type of jobs you desire.


Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.