demands from the elder population account for the rise of both invasive and non-invasive procedures comprising biomaterial implantation. [2] Substantial progress was made in terms of mechanical properties, biocompatibility, and biointegration resulting in excellent functional outcomes in multiple surgical specialties. On the other hand, there is to this date no consensus for an anti-infectious strategy in order to prevent biofilm formation on implanted surfaces. The consequences of nosocomial infections arising from surgical implants still represent a heavy burden on both patients and healthcare systems worldwide. [3] In spite of the advancements of antisepsis procedures, a significant and fixed proportion of nosocomial infections are still reported (from 1 to 2% for hip and knee joint replacement, respectively). Biofilm is an exopolysaccharidic matrix comprising bacteria with reduced antibiotic sensitivity and poor mechanical accessibility. [4-6] Biofilm formation plays a major role in the failure of conservative treatments (antibiotic use, wound debridement, and lavage) for implant-related infections. [7,8] A common rule is to perform implant removal to treat biofilm-related infections if a proper conservative treatment has previously failed, which explains the high morbidity caused by the management of A quaternized polyvinylpyridine (Q-PVP) polymer methanolic solution synthesized in a single step is used to covalently graft titanium surfaces. Q-PVP is quaternized with varying N + /N ratios. 1 cm 2 pure titanium plates are polished and activated. Treated samples are grafted by spin coating or dip-coating (grafting-to method). Surfaces are characterized by X-ray photoelectron spectroscopy, polarization modulation reflection absorption IR spectroscopy, atomic force microscopy, scanning electron microscopy, and surface charge density calculation. Polymer leaching is assessed at 7 days. Biocompatibility is assessed on MC3T3 and L929 cells (MTT-assay) and SEM. In vitro antibacterial activity is assessed on methicillin-resistant Staphylococcus aureus (MRSA) at 1 and 24 h (37 °C in brain heart infusion) and at 7 days in a biofilm model. Polymers exceeding 31.3 ± 0.7% quaternization led to bactericidal surfaces. Bactericidal activity increased with surface cationic density. Surface cationic density and biocompatibility are inversely correlated. Polymers with 44.6 ± 1.2% quaternization are antibacterial and biocompatible. High-density Q-PVP inhibited MRSA biofilm formation. Q-PVP is a promising candidate for antibacterial surface modification. Further in vivo studies are required.