Since publication of the Multicenter Automatic Defibrillator Implantation Trial (MADIT) in 1996, indications for implantation of implantable cardioverter defibrillators (ICDs) have expanded. Initial criticisms of the study have been addressed, including the need to await the conclusion of several additional ICD clinical trials. These other trials have generally shown an improved survival with ICD therapy when compared with antiarrhythmic agents. As a result, ICD implantation volumes have increased worldwide. However, ICD usage has regional variation with 120 implants per million population in the United States, 45 per million in Germany, but only 7 and 8 per million in France and the United Kingdom, respectively. Although many factors affect implant decisions, reimbursement issues are particularly important. Other factors may explain the slower growth in Europe when compared with the United States including greater skepticism regarding MADIT, less industry-sponsored marketing, and lack of unified cardiology society support for the MADIT recommendations. Nevertheless, it is anticipated that >50,000 ICDs have been implanted worldwide in 1998, with a growing percentage in the countries of Europe.