Indications for hemodynamic assessment by right heart catheterization include shock, pulmonary edema, severe trauma and sepsis. The introduction of the catheter and the location of the tip in the pulmonary artery, however, can cause severe complications. In the present study the incidence of complications was observed in 93 consecutive right heart catheterizations in critically ill patients with no evidence of recent myocardial infarction. The low incidence of complications during introduction and with the catheter tip located in the pulmonary artery justifies right heart catheterization in patients with hemodynamic and/or respiratory instability treated in an intensive care unit.