First, let's just say that any Atheists and/or Agnostics may feel free to replace the word "God" with "nature" throughout this article.
Second, I am going to play devil's advocate - pardon the irony - to those who believe plastic surgery is somehow morally wrong because "Who are we to mess with what God made?"
If God brought you into this world in poverty, do you owe it to Him to stay there?
If you were born with webbed fingers, is it an insult to God (and therefore, a sin) to have your deformity corrected so your hands can be fully functional?
If God decided you were meant to lose your eyesight (even when there's a laser surgery that could preserve it), do you think He would be offended if you had the surgery?
Now you may be thinking that these questions are not relevant to cosmetic surgery because these things are all related to health and function, not vanity. Okay then. I have to ask you now: Did God give you pierced ears? Did God give you cut, styled, and colored hair? Did He make you with colored eyelids and glossy lips and painted nails and powdered skin? Were you born with clothes on?
Of course I'm not implying that everyone should run out and have plastic surgery. I'm not speculating that God likes plastic surgery, or saying that vanity is a good thing (although I don't believe a little vanity is necessarily a bad thing either). I'm just saying, if you believe in God, you must also believe that He gave us each certain gifts that we can use to improve our health, our station in life, our base of knowledge, and yes, even our appearance. When someone gives you a gift, isn't it fair to assume they want you to use and enjoy it?
Still others disparage cosmetic surgery as a selfish act. Well, yes...and no. To keep this post from getting too long, I'm going to refer you to another post about the morality of having plastic surgery in these trying times. Maybe it will help you see things from a new perspective.
Agree with me? Disagree? Let your feelings be heard by taking part in this related poll on the morality of plastic surgery.
To sum it up, I never read anything in the Bible (and I don't believe it is in any other Holy books either) that says "Thou shalt not have plastic surgery". I have, however, read the part where it says, "Judge not, lest ye be judged." And that's good enough for me.

This topic of Christianity and breast implants surgery cropped up today on our Q&A with plastic surgeons. Interesting discussion where the plastic surgeons clearly do not see a conflict with Christian Beliefs.