The elderly patient is susceptible to a variety of cardiac rhythm disturbances that may or may not cause symptoms. It is incumbent on the physician who cares for geriatric patients to have a familiarity with the diagnostic criteria for each of these arrhythmias and with the drugs and devices that are used to treat them. This includes the potential adverse effects of therapy and methods to counter them. Even more important is a sense of when to intervene, which is based, in large measure, on a knowledge of "normal variation" in the aged.