The pulmonary artery catheter (PAC) has been in use for more than 30 years. The amount and detail of hemodynamic information provided by the PAC cannot be matched by any other single technology. Whether or not this information makes a difference in the clinical outcomes of critically ill patients is uncertain, however. The Pulmonary Artery Catheter Consensus Conference scrutinized the available research data on the catheter and provided guidelines for clinicians on its use. This article summarizes the controversy and the guidelines available for use of the PAC. It notes the need for further research on patient outcomes.