The Swan-Ganz catheter provides a relatively easy means of obtaining a wealth of information about intracardiac pressures and flows. The catheter also is useful for intracardiac pacing. Because any invasive procedure entails some risk, albeit small in the case of the Swan-Ganz catheter, insertion of a catheter usually is reserved for hemodynamically unstable patients and/or those in whom information relevant to clinical management can be obtained only by this means. In such circumstances the catheter has been extraordinarily useful, and further refinements undoubtedly will make it even more useful in the future.