i had to do this, actually... i keep meaning to post this as a cautionary tale but just haven't. i wrote a letter of intent to emory back in october and got passed over by them four times (they do a batch of acceptances every month and then everyone hears in march). then in february i was offered a totally unexpected interview at harvard. needless to say, harvard was amazing, and i was kicking myself at the very remote possibility of getting into both harvard and emory (they released final decisions at about the same time) and having to go to emory. i should note that i had already been accepted at my third choice, einstein, which helped things a lot. anyway, i dithered about it for a week or so until a friend of mine asked me, "what will you regret more, sabotaging your chances at emory, not getting into harvard, and winding up at einstein, or getting into harvard and not being able to go?" that cleared things up for me. i decided to go for it and rescinded my loi at emory. amazingly, the lady who answered the phone said she would just remove it from my file and not report it or anything. so presumably it had no effect on my application, though i was waitlisted a month later. i wound up not getting into harvard (surprise, surprise). well, i'm happy with my choice, and i would have been even if i had gotten into emory. einstein will be awesome. op, you have to look at your options and figure out what the worst case scenario is for each option and see which one you can live with.