I receive many queries from clients regarding thank you notes after residency interviews. The most recent program directors survey done by the National Residency Matching Program suggests that such follow up notes do not impact ranking but I still recommend that applicants send them. Expressing gratitude suggests that you are courteous and professional and therefore I always advise sending them. Since most faculty are hooked on email, it is acceptable to send thank you emails unless the program specifically instructs otherwise.
On a personal note, when I was a residency admissions officer and received such letters from applicants, they often ended up in the recycle bin even though it made a good impression. These notes never impacted the decision that I made regarding an applicant's candidacy or ranking.
So, what should you write? These notes should be brief (one or two paragraphs) unless you discussed something specific and unusual with an interviewer. You should thank the interviewer for their time, try to mention something specific from your interview and discuss what you liked about the program.
You should wait to tell a program that they are your #1 choice until the end of interview season and then write a letter of intent.
Do you need help with your interview season strategy or letter of intent? Contact MedEdits.