Bacteria are important in causing biliary stent blockage through adherence and subsequent biofilm formation. In our in vitro system, surface modification using test polyurethane discs with silver coating led to a reduction in the number of adherent bacteria compared with untreated controls by 10- to 100-fold in an apparently dose-related manner. The effect was more marked in the presence of bile. These results suggest that silver coating may have a potential benefit in preventing stent blockage.