The present study deals with the demonstration of deposited fibronectin (Fn) on the surfaces of implanted biliary drain materials and the role of deposited Fn in promotion of bacterial adherence. Rubber pieces that had been implanted in the biliary tracts of rats for 4 weeks were retrieved and the following approaches employed for further investigations: (1) adherence of [methyl-3H]thymidine-labeled Escherichia coli to implanted and unimplanted rubber pieces; (2) blocking the adherence of radiolabeled bacteria with anti-Fn antibodies; (3) detection of deposited Fn by 125I-labeled anti-Fn IgG; and (4) immunoblotting of the surface eluate from implanted rubber pieces. The results show that in the presence of serum, plasma, or bile, the number of E. coli cells adherent to implanted rubber pieces was 10 times higher than that adherent to the unimplanted pieces (P < 0.001) and that the adherence was reduced by pretreatment of implanted pieces with anti-Fn antibodies. Furthermore, the implanted pieces appeared to have a high affinity for 125I-labeled rabbit anti-Fn IgG rather than the 125I-IgG without anti-Fn fraction. Fn was also found in the surface eluate of implanted pieces by immunoblotting of the eluate. The results in the present study suggest that Fn may be involved in implant-associated infections in the biliary tract.