Community- or hospital-acquired infection proved to be a contributoryfactor to a fatal outcome or the direct cause of death in more than one-halfof patients in the intensive care unit. Infections occur five to ten times moreoften in ICUs than in non-ICU settings and significantly increasemorbidity, mortality and length of stay in the ICU. Fortunately, majoradvances have been made in our understanding of patterns of infection incritically ill patients and how to diagnose these infections expeditiously andaccurately. Potent anti-infectives are now available to treat every type ofbacterial infection, nearly all fungal infections, most parasitic infections,and increasing number of viral infections. Prevention of nosocomialinfections requires coordination among ICU staff, infectious diseasespecialists, microbiologists, hospital infection control practitioners and thehospital epidemiologists.