Pulmonary artery catheterization has been widely used for cardiac output and hemodynamic monitoring. However, the clinical usefulness of pulmonary artery catheterization has been questioned because its use does not necessarily improve prognosis. Fortunately, alternatives to pulmonary artery catheterization have emerged. The pulse contour method monitors the beat-by-beat stroke volume based on an analysis of the arterial pressure waveform, while the partial carbon dioxide rebreathing technique monitors cardiac output by applying the indirect Fick method to carbon dioxide. The esophageal Doppler method approximates cardiac output based on the descending aortic blood flow. Echocardiography and transpulmonary thermodilution not only measure cardiac output, they also provide additional information regarding its determinants. Pulse pressure variation and stroke volume variation are capable of predicting the hemodynamic effects of volume loading. Central venous oxygen saturation, an indicator of the imbalance between oxygen supply and demand, can be monitored continuously using a specific central venous catheter. Here, we address the clinical potentials and limitations of these technologies.