There is growing evidence that some class III antiarrhythmic drugs, unlike class I agents, are not associated with an increased risk of death in patients with prior myocardial infarction and left ventricular dysfunction. 1‐14 For this reason, we evaluated the extent to which the current prescribing of antiarrhythmic medications complies with the evidence that supports the use of class III rather than class I agents. Using pharmaceutical marketing research data, we reviewed outpatient antiarrhythmic drug prescriptions in the United States from 1995 through the third quarter of 2000, to characterize the prescribing of these drugs and to examine drug use trends over this period. ••• Data on antiarrhythmic drug prescribing were derived from 2 audits owned by IMS Health (Plymouth Meeting, Pennsylvania): the National Prescription Audit (NPA) Plus and the National Disease and Therapeutic Index (NDTI). The NPA Plus audit measures the retail outflow of prescriptions in the United States. This includes prescriptions dispensed by retail pharmacies and mailorder pharmacies. The NDTI audit contains data on drug mentions associated with a diagnosis during a specific clinic visit. These data are collected by a continuing survey of 343,655 physicians in officebased practices in the United States. An NDTI panel of physicians, a subset of 343,655, is selected every 2 weeks to provide demographic information, diagnoses, and recommended drugs for each diagnosis on all patients encountered. This is then projected to the national level. The NPA Plus audit was queried for all class I and class III antiarrhythmic drugs for which an oral dosage form was marketed and sold in the United States between January 1995 and September 2000. The numbers presented for the year 2000 represent a 9-month period. Class I agents included the class IA agents quinidine, procainamide, and disopyramide, the class IB agents mexiletine and tocainide, and the class IC agents flecainide, propafenone, and moricizine. Class III agents included amiodarone and sotalol. We limited this analysis to class I and III antiarrhythmic drugs because it would be difficult to determine whether blockers (class II antiarrhythmic agents) and calcium channel blockers (class IV antiarrhythmic agents) were prescribed solely for an arrhythmic indication. The NDTI audit was queried for all oral class I and class III antiarrhythmic agents strati fied by physician specialty and diagnoses for which the agent(s) was used. Trends in antiarrhythmic drug prescriptions were evaluated based on physician specialty and the diagnosis for which each agent or class of agents was reported to be prescribed.