A serious complication of hernioplasty with the use of a biomaterial implant is deep surgical site infection (SSI) encompassing the implant. Among the most common etiological factors of deep SSI in patients after hernioplasty are Staphylococcus aureus and Escherichia coli strains, which may create a biofilm on the surface of synthetic implants. The aim of this study was assessment of biofilm formation by S. aureus and E. coli on the surface ofpolypropylene mesh. The study included 108 strains (62 S. aureus and 46 E. coli) from the collection of Department of Microbiology Collegium Medicum im. L. Rydygier in Bydgoszcz, Nicolaus Copernicus University in Torun (CM UMK). Evaluation of biofilm formation was performed using the method of reduction of 2,3,5-triphenyltetrazolium chloride (TTC) and a scanning electron microscope. In the group of S. aureus strains, 88.7% isolates formed biofilm very strongly, 1.6% strongly, and 9.7% poor. Among E. coli strains, 54.3% isolates were characterized by very strong biofilm formation, while 45.7% strong biofilm formation. Strains ofS. aureus strongly than E. coli form a biofilm on the surface of monofilament polypropylene mesh.