Bacterial colonization potentials by Staphylococcus aureus (Staph. aureus) were determined in silver peritoneal dialysis (PD) catheter materials and were compared to colonization of the same bacteria in silastic catheter materials. The bacteria were colonized in two different experimental systems: In Vitro: In an in vitro biofilm bacterial culture system with a modified Robbins' device (MRD), seven different clinical strains of Staph. aureus were grown in PD effluents on silver or silastic catheter discs, each 0.5 cm in diameter. In identical experimental conditions, reduced bacterial growth was detected in silver catheter discs compared to growth on silastic discs, but the results were not statistically different (p = 0.12). In Vivo: In a rabbit model of PD the, in vivo colonization potential of Staph. aureus was examined in two groups of rabbits using silver (n = 3) and silastic (n = 3) PD catheters. The exit sites of the PD catheters were inoculated with a single strain of Staph. aureus for six days, followed by PD for six days. The rabbits were then sacrificed. After sacrifice, comparison between the bacterial counts of identical segments of silver and silastic catheters showed that there had been a reduction in the growth of Staph. aureus in vivo on silver PD catheters, contrary to the increased growth on the silastic catheters (p < 0.05). Reduced bacterial growth on the silver PD catheters in vivo indicates that the release of silver in tissues over time cause antibacterial effects in vivo. Further in vivo experiments are needed before future clinical use of silver catheters in PD patients.