Basic concepts are presented for the use of polypropylene mesh in gynecology for prolapse and stress-incontinence repair. The vagina is a clean-contaminated environment, and it is not possible to insert polypropylene mesh devices without bacterial contamination, despite standard antibiotic usage. Once inserted, the host tissue immediately attaches to the polypropylene and attempts to defend it from bacterial invasion, but if the bacteria have already reached the surface of the device, then dislodgement is difficult. The devices with larger surface areas result in greater bacterial contamination, more polypropylene degradation, increased inflammatory response, fibrous tissue stimulation, and erosion. Noninert polypropylene degrades into potentially toxic compounds that would be expected to stimulate a greater inflammatory reaction leading to erosion. If the physician does not place the mesh below full-thickness vaginal epithelium, penetrates the epithelium during insertion, or if there is hematoma formation near the vaginal incision, then defective healing and erosion may result. Scar tissue causes contraction to less than 50% of the implanted size, which results in dyspareunia and tension on the pelvic mesh attachments. Such contraction may cause pelvic pain and subsequent erosion into adjacent organs. An individual response in fibrosis also exists, with some individuals being "high responders." Manufacturers need encouragement to develop meshes that are inert and incorporate without contraction along with routine clinical tests to detect "high responders" to avoid complications. Polypropylene is not inert within the human body.