The frequency of reports about postoperative complications after implantation of hernia meshes seems to point to a deficit in their biocompatibility. A simple experiment was designed to show the effect of resterilization which is allowed by some manufacturers of the meshes on their surface structure that should be important for biocompatibility. Two common lightweight polypropylene hernia meshes (Optilene® LP, Atrium® pro lite) were examined with an electron microscope before and after incubation with MRC 5 cells which are used as a model for human fibroblasts in this experiment. Atrium® prolite which was additionally resterilized due to the manufacturers recommendation in a steam autoclave for 20 min at 121 °C was treated to the same procedure as the two native meshes. Then the images made with the electron microscope where compared to each other. The sterile hernia meshes showed differences in respect to their surface structure when taken out of the packaging. Besides irregularities in their filamentary structure (Atrium® prolite, Optilene® LP) they showed artefacts (Optilene® LP) which were not attributable to the mesh and possibly were due to the manufacturing process. The Atrium®-mesh treated in the autoclave showed multiple fissures on the micrometer level and small bubbles which were not shown by the Atrium®-mesh not treated with the autoclave. After 72 h of incubation with MRC 5 cells and cell culture medium a progress was discernible in respect to the morphological change. Light weight polypropylene hernia meshes were developed to improve their biocompatibility. Some manufacturers offer the possibility of resterilization of lightweight hernia meshes which were taken out of their packaging for one time. That means a clear reduction of the cost for material. This experiment which was deliberately kept simple shows that treatment with the autoclave results in visible changes on the filament surface of light weight hernia meshes which are increased after incubation with human connective tissue cells and cell culture medium. Because hernia meshes are supposed to remain in the human body for life there could be an increase of changes of the surface structure in the course of time which would probably have a negative effect on the biocompatibility of the meshes.