Blood stream infections are an important complication of the use of central venous lines (CVLs) and result in increased morbidity, mortality, and cost. Blood stream infections related to CVLs may be the result of migration of skin organisms along the catheter tract or introduction of organisms into the lumen of the catheter. The extraluminal route of infection appears to be most common early after catheter insertion while the frequency of infection acquired by the intraluminal route appears to increase the longer the catheter is in place. Meticulous attention to best practices for insertion and the subsequent care of the insertion site reduces infection by the extraluminal route. Adherence to good technique for entering the line may similarly reduce infection by the intraluminal route.