It says 100% cotton top but its almost fully polyester! When I got the package and saw that the box was too small I thought something was wrong. I took it out and saw this thin mattress pad! It was 100% polyester and on the back it says 100% cotton padding. Don't buy this if you expected more for your money. You should set out to your local ***** or ***** and invest on a nice pad that you can see and feel. The way they described the item.. it's almost false advertising... it should be 95% polyester with 5% cotton padding. If you want a cheap mattress pad made out of cheap materials, then I suggest you buy this one. But if you want a quality one, buy one from a local store.