Letters of recommendation are one of the few parts of your application written by someone else — which is exactly why they carry weight. A strong letter corroborates the story your essays tell. A generic one quietly hurts you. This guide covers who to ask, how many you need, when to ask, and how to set your writers up to advocate for you effectively.
Requirements vary by school, so always check each one, but a common, safe combination is:
Many undergraduates also have access to a committee letter — a single packet assembled by their school's pre-health advising office. If your school offers one, use it; admissions committees expect it when it's available.
The best letter writer is not the most famous or highest-titled person you know — it's the one who knows you well and likes your work. A lecturer who saw you grow over two courses and office-hour conversations will write something far more convincing than a department chair who knows you as a name in a 300-person lecture. Choose relationship over prestige every time.
Ask six to eight weeks before you need the letter submitted — earlier is better, since professors are busy and quality letters take time. The ideal moment to plant the seed is while the relationship is fresh: at the end of a course you did well in, or after a meaningful research or clinical stretch. You can ask them to write it later, but locking in the "yes" early protects you.
Even a writer who likes you can't remember every detail. Hand them a short document that makes writing easy:
Most letters are uploaded through services like Interfolio or sent directly to the application service (AMCAS, AACOMAS). Waive your right to view the letter when given the option — confidential letters are taken far more seriously by committees. Send a polite reminder about a week before the deadline, and always follow up with a genuine thank-you note once it's submitted.
If you've been out of school for years, the standard "two undergraduate science professors" advice can feel impossible — those professors may barely remember you. Don't force it. Admissions committees understand non-traditional timelines, and a vivid letter from a recent post-bacc instructor who taught you last semester beats a hollow one from an undergraduate professor who can only confirm you attended. Prioritize, in order: current post-bacc science professors, current clinical or work supervisors, and a physician who has watched you with patients. If a school's stated requirement seems incompatible with your situation, email their admissions office and ask — most have a documented process for non-traditional applicants.
Some undergraduate institutions (and many formal post-bacc programs) offer a committee letter — a single document, assembled by the pre-health office, that summarizes and often bundles your individual letters. When your school offers one, schools expect it, and not using it can raise questions. If your school doesn't offer one (common for non-traditional applicants), that's completely fine — you simply submit individual letters, and committees won't hold its absence against you. If you're unsure, ask your pre-health advising office directly how their process works and when their internal deadlines fall, since committee letters often require you to start months earlier than you'd expect.
Most letters reach application services through one of a few channels: Interfolio (a paid dossier service that stores letters and sends them on your behalf), the AMCAS Letter Service (where writers or your school upload directly), or a school-specific portal. Set each letter up correctly in your application by creating a "letter entry" and giving your writer the unique ID or upload link they need. Always waive your right to view the letter when given the option — confidential letters carry far more weight, because committees trust that they're candid.
Most schools want three to five. A common set is two science professors, one non-science professor, and one physician or clinical supervisor — but always check each school's specific requirement.
Consider asking someone else. A lukewarm "yes" often produces a lukewarm letter. Phrasing your request as "a strong letter" gives reluctant writers a graceful way to decline.
A small number of extra, high-quality letters can help, but don't pad your file. Two outstanding letters beat five mediocre ones, and some schools cap how many they'll read.
Almost always. Confidential (waived) letters are taken far more seriously because committees trust they're honest. Choose writers you're confident will advocate for you, then waive.