Physicians must now consider the likely cost of management decisions as well as the expected effects on patient outcome. Cost-ascertainment studies identify and contrast the cost of therapies, and cost-effectiveness analysis compares the additional cost of a therapy with its additional effect on survival and quality of life. This article reviews the principles of cost-ascertainment and cost-effectiveness analysis and then presents the cost of initial and follow-up care in Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial. Finally, the cost-effectiveness of therapy guided by electrophysiologic study or Holter monitoring and of sotalol versus other drugs is reviewed, and implications for future studies are discussed.