I ordered a small and medium because i was worried about the chest being too tight (i am 5'6", 140 lbs, 34d) but i was swimming in a size medium. it was huge. the small really fits me just fine. my only issue is that the very bottom of the sleeves is tight. i would like to push them up a little since they are 3/4 length, but they are tight. i am still keeping the small though....maybe i'll do surgery on the cuffs!