Residency Letters of Recommendation - How many do you need?
For most specialties, you need four letters:
PhD advisor
The program director or chair of the department in which you are applying (often comes from your Sub-I, but can be also from a strong clerkship experience); multiple people may contribute to this letter which will be signed by the chair.
MD of your choice
MD of your choice
For letters 3 and 4, whether they come from physicians in your specialty or others may depend on the residency in which you are applying. They can be from attendings with whom you’ve worked over the third and fourth year and do not need to be people that you have known very well over several years. Someone who has seen you in both clinical and research worlds - although hard to come by - can be a great letter writer. A good letter could come from 2 weeks of meaningful clinical encounters.
Note for MD/PhD students:
The MSPE that includes the MSTP Director letter does NOT count towards your 4 letters. None of the clinical letters will match the depth and breadth of content that your PhD advisor will be able to write because that person will know you for much longer than the clinicians who may know you for a few weeks, usually at the most