This study addresses current costs of implanting implantable cardioverter defibrillators (ICDs) at one large medical center and documents actual costs using two methodologies. To determine the actual cost of ICD therapy, we studied all ICD implants performed in the procedure room (similar to an electrophysiology laboratory) who met accepted secondary prevention (AVID) indications for a 1-year period at Loyola University Medical Center. The study period coincided with the facility's shift of this procedure out of the operating room to a procedure room. Costs were analyzed two ways: a cost-based analysis and a cost-to-charge ratio analysis based on the facility's Medicare Cost Report. Twenty-four patients (14 inpatients and 10 outpatients) met the study inclusion criteria. Length of stay averaged 5.8 days for inpatients and 1.1 days for outpatients. In the cost-based analysis, the mean costs of the ICD implant (device, implant procedure, and preimplant and postimplant stay) were $33,509 for inpatient and $28,078 for outpatient implants. In the cost-to-charge ratio analysis, the mean costs for the inpatient hospitalization were $35,623. This is one of the first studies to document cost of ICD therapy and may serve as a benchmark for other facilities.