After its introduction in 1970, the use of the pulmonary artery catheter became a central part of the management of critically ill patients in adult and pediatric intensive care units. However, because it was introduced as a class II device, efficacy for its safety and clinical benefit did not exist during the early years of use. This review describes the pulmonary artery catheter and reviews the literature supporting its use.A search of MEDLINE, PubMed, and the Cochrane Database was made to find literature about pulmonary artery catheter use. Literature for both adult and pediatric patients was reviewed. Guidelines published by the Society for Critical Care Medicine and the American Heart Association were reviewed, including further review of references cited.The evidence supporting the use of the pulmonary artery catheter is mostly limited to level IV (nonrandomized, historical controls, and expert opinion) and level V (case series, uncontrolled studies, and expert opinion). A higher level of evidence supports the use of the pulmonary artery catheter in selected pediatric patients, especially those with pulmonary arterial hypertension and shock refractory to standard fluid resuscitation and vasoactive agents. There are no data to suggest that use of the pulmonary artery catheter increases mortality in children.