Kim Kardashian Bikini Pictures

Kim Kardashian turns 31 today, and we're celebrating the major milestone with a look back at her sexiest bikini pictures! It's been a big year, so far, for Kim and her family. Kim marrried Kris Humphries in August and scored a solid fourth-place finish in our 2011 PopSugar bikini bracket over the Summer. Happy birthday, Kim — here's to another year full of great bikini moments!