Pulmonary artery catheterization is currently used for more than 25 years for the hemodynamic monitoring of critically ill patients. As for every monitoring technique, its indication is based on the goal, that knowledge of the obtained additional hemodynamic parameters may lead to an optimization of therapy and thereby to an improvement in patients'outcome. Despite of the presence of clinical studies which documented changes in therapy following such extended monitoring, there is no clear proof for a positive effect on patients' mortality. While some of the available studies showed a benefit by pulmonary artery catheterization, others did not or even demonstrated a negative effect. However, no study fulfilled the scientific requirements which enables to make a statement to the effectiveness of pulmonary artery catheterization by objective criteria. The purpose of this review article is to summarize the currently available literature with regard to the effectiveness of pulmonary artery catheterization in the critically ill patient.