Vascular catheters are a common source of nosocomial infections, although many of these infections are potentially preventable. A long duration of catheterization, multiple catheter manipulations, the inexperience of some inserters, use of transparent plastic dressings, violations of aseptic technique, the use of multilumen catheters, and inadequate sterilization of reusable pressure transducers all increase the risk of these infections. The only interventions that have been proved to reduce the risk are standardized insertion and maintenance technique by an intravenous-therapy team, preinsertion skin preparation with chlorhexidine gluconate, and the use of topical antibiotics at the insertion site. The goal of the physician should be to prevent catheter infection, because the treatment of established infection can be difficult and costly. Treatment must be individualized for each patient on the basis of the clinical presentation and the causative organism.