What do you do when your best friend cheats and has become top 10 in class of 250? My very best friend cheats, not just looking over her shoulder for two answers, I mean full out cheats - raising each grade from what would be a D to an A. I feel very guilty for doing something wrong, so I can not cheat. 

I have a rank 35 in the school (I have only made 3 B's in 4 years of school). Most students above that cheat constantly. She takes mostly AP classes and I do too, but I am getting very frustrated that she and others look very intelligent when they cheat on the whole test before hand. My friend always brags about how she will be awarded a very prestigious award for her grades in Calculus, but my friend just told me she cheats on all the tests. Just recently she got a list of all the answers for a test and just bubbled each in knowing nothing. She will be awarded with many awards she does not deserve. I just don't think it is fair considering colleges look at rankings.

I don't want to lose my friendship with a really close friend, but I can't let this stand. I have tried warning her it was a bad idea. She wants to be a medical doctor and I feel like its important now for her to not cheat. People say that bad things will happen in the future because of what she does now, but I honestly believe she will continue to cheat without consequences.

Side-note: Another friend said, "Why would it matter if she cheats, that isn't affecting you." I just feel like it is affecting me when rank is what colleges look at.

What should I do?
You say that several students are cheating. This is actually good in the sense that you maybe can avoid specifically naming your friend.

One option is to contact a relevant faculty member (ideally one that you know and trust) and say that you know that several of the top graders are cheating. A second option is to do this anonymously.

The advantage of doing this anonymously is obviously that people will not know that you reported this. The disadvantage is that it may be less credible.

BTW your friend is completely incorrect. It definitely does affect you, since the ranking and the prizes can affect your future career. If she can't understand that, then she perhaps isn't such a good friend.