I actually was under the impression that these shirts were mostly cotton as that is originally how I did the search. They are not - they are mostly rayon, but I am NOT UNHAPPY at all. This shirt is comfy and stylishly loose, but very well designed, cool fabric, light and smooth. I like it a lot! I am 5'6', about 140, 36D top. I like my tops long to cover down to my butt and this one does. The arms are comfortable and do not show my bra. I can dress it down for around the house or dress it up a bSee full review