Polypropylene (PP, also polypropene), is made via chain-growth polymerization from the monomer propylene.

Polypropylene belongs to the group of polyolefins. Its properties are similar to polyethylene, but harder and more heat resistant. It has a high chemical resistance.
Polypropylene is the second-most widely produced commodity plastic after polyethylene.

In medicine it is used mostly in filaments like sutures and meshes.
Mesh implants are used to prevent prolapses of tissue like hernias. However, a polypropylene mesh may erode the tissue surrounding it over the uncertain period from days to years.

A notable application was as a transvaginal mesh, used to treat vaginal prolapse and concurrent urinary incontinence. Due to the above-mentioned propensity for polypropylene mesh to erode the tissue surrounding it, the FDA has issued several warnings on the use of polypropylene mesh medical kits for certain applications in pelvic organ prolapse, specifically when introduced in close proximity to the vaginal wall due to a continued increase in number of mesh-driven tissue erosions reported by patients over the past few years.