Nathan,

No, it is not a sin. Plastic surgery is often an important part of treatment for many people who have been disfigured by injury or illness.

I assume you may be referring to elective and gratuitous plastic surgery for appearance enhancement. This is a very subjective judgement and we can leave it to the individual and God to work it out.

There isn't any clear line that we can point to. It is better to remain charitable toward those who elect to do so, albeit we often witness procedures that appear more detrimental than beneficial.

Peace,

Bob Kirby