Of 142 critically ill patients undergoing pulmonary artery catheter (PAC) insertion, 1.4% suffered pneumothorax and 7.7% experienced arterial puncture during central venous access. Catheterization was successful in all cases; however, 8.4% of patients required special maneuvers for pulmonary artery cannulation. The 52.3% incidence of cardiac arrhythmias during PAC insertion was primarily due to ventricular arrhythmia (VA), which was more common among patients with complicated myocardial infarction (p<.01) and less common in patients with sepsis (p< .05). The development of VA was significantly related to the duration of PAC insertion. Our study suggests that PAC placement carries certain risks and complications which should be weighed against the advantages of a PAC in each patient.