Nosocomial infections are a leading cause of morbidity and mortality among hospitalized patients. These infections have made newspaper headlines recently in many countries, and both patients and their relatives are now perfectly aware of their existence and of the risks which are inherent to any medical activity. However, significant improvements in the knowledge of the pathophysiology and epidemiology of nosocomial infections allow us to prevent them efficiently. Accordingly, they should no longer be considered as an inevitable tribute to pay to the continuous progress of medicine, but as a real challenge in the process of improving the quality of patient care. This is particularly the case for bloodstream infections, of which at least 80% are considered to be catheter associated. This paper reviews the epidemiology and impact of infections associated with the use of intravenous catheters. Principles of therapy are reviewed, as well as major aspects of prevention.