Infection, thrombosis, and stenosis are among the most frequent complications associated with blood contacting catheters. Because these problems are usually related to surface properties of the base catheter material, surface treatment processes, such as ion implantation and ion beam assisted deposition (IBAD) (silver based coatings), can be used to mitigate such complications. Because these ion beam based processes affect only the near-surface region (approximately the outer 1 microm), there is little effect on bulk material properties. This study evaluated silver coated and implanted large bore catheters used for extracorporeal detoxification. In a 186 patient prospective study, 225 large bore catheters were inserted into the internal jugular or subclavian veins. 85 surface treated catheters (Spi-Argent, Spire Corporation, Bedford, MA-USA; n=39 acute catheters, n= 46 long-term catheters) and 28 catheters with surface treatment (Spi-Silicone, Spire Corporation, Bedford, MA-USA) were inserted in 90 patients. 112 untreated catheters placed in 96 patients served as controls (n = 62 acute catheters, n = 58 long-term catheters). After removal, the catheters were cultured for bacterial colonization using standard microbiologic assays. They also were examined using a scanning electron microscope (SEM). Bacterial colonization was observed in 8% of the treated catheters compared with 46.4% of untreated catheters. The SEM investigations showed all treated catheters to possess low thrombogenicity. Results of the study indicate that ion beam based processes can be used to improve thrombus and infection resistance of blood contacting catheters.