The polypropylene is the "scrim" that the batting is needled through to make it stable. The batting is 100% cotton, but the scrim (very, very thin mesh) is the poly-whatcha-callit!! If that little bit of poly bothers you, you can take your chances with batting that is not stabilized, and will probably separate and bunch after a few washings. I'll take the poly-whozit to be sure the batting stays put in my quilts! Just MHO.