I am applying for a PhD in tumor biology in the United States. Most institutions require 3 letters of recommendation. I currently work at a lab doing cancer research where I have two PIs as my bosses. Previously I have worked at a different biology lab, as well as as a medical assistant.

I am planning to ask the PI from my previous lab for a recommendation letter, as well one of my bosses at my current lab, but am unsure whom I should ask for the third. My options are either my other boss from my current lab, or the doctor I worked for as a medical assistant. The work I do at my current position would be more relevant to my application, but I worry that the letter from my second boss would not add much as I would already have a letter for the same work.

Would it be better to ask for the more relevant but potentially redundant letter or the professional one?

1 Answer 1


Given your field, it might not matter a lot, but don't miss the purpose of "redundant" letters. It isn't that they might say the same thing, but that they are from independent people that makes them important. Otherwise, a single letter would do.

What you want heard by the committee is that you have a high probability of success in the program and thereafter. But it is success in an academic program. If the program had clinical aspects then a letter from a working doctor might be more important.

In some sense, you hope the letters are redundant.

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