Ion beam-based processes such as ion implantation (silicone rubber) and ion beam-assisted deposition (silver-based coatings) affect the outer micron layers of catheter surfaces. These processes were used on the common catheter materials of silicone and polyurethane. In 56 rats, surface (Spi-Silicone and Spi-Argent I and II) catheter segments were implanted for 1, 3, and 6 weeks. After removal, these pieces were investigated for bacterial colonization and fixed for scanning electron microscopic evaluation. As controls, untreated catheter segments were implanted in 28 rats. Bacterial colonization was found in 2.4% in the surface treated catheter pieces versus 7.1% in the control group. The scanning electron microscope investigations showed low thrombogenicity in all of the treated catheters independent of the implantation times.