The safety and efficacy of catheter ablation for the treatment of drug refractory cardiac arrhythmias is well established in young patients. Little is known about its effectiveness or use in the elderly. We determined trends in the use of catheter ablation in the United States Medicare population. Data were obtained from the approximately 30 million patients covered each year by Medicare's fee-for-service program of the Health Care Financing Administration of the Department of Health and Human Services. From 1991 to 1998, Medicare's fee-for-service beneficiaries covered 80%-93% of all adults > 65 years old in the United States. All catheter-based ablative procedures performed in this population were identified through the use of the Current Procedural Terminology codes 93650, 93651, and 93652. Use rate per 1 million beneficiaries grew from 33 in 1991 to 603 in 1998. While during this 7-year period the Medicare fee-for-service population decreased by 8%, ablations increased 16-fold (1,608%). The use of catheter ablation in the older American grew exponentially during the 1990s. Further research is needed to determine the optimal use of this potentially curative technique in the elderly.