Patients with implantable cardioverter defibrillators (ICDs) can require antiarrhythmic drugs to manage arrhythmias and prevent device shocks. We sought to determine the prevalence, clinical correlates, and institutional variation in the use of antiarrhythmic drugs over time after ICD implantation. From the ICD Registry (2006 to 2011), we analyzed the trends in the use of antiarrhythmic agents prescribed at hospital discharge for patients undergoing first-time ICD placement. The patient, provider, and facility level variables associated with antiarrhythmic use were determined using multivariate logistic regression models. A median odds ratio was calculated to assess the hospital-level variation in the use of antiarrhythmic drugs. Of the cohort (n = 500,995), 15% had received an antiarrhythmic drug at discharge. The use of class III agents increased modestly (13.9% to 14.9%, p <0.01). Amiodarone was the most commonly prescribed drug (82%) followed by sotalol (10%). Among the subgroups, the greatest increase in prescribing was for patients who had received a secondary prevention ICD (26% in 2006% and 30% in 2011, p <0.01) or with a history of ventricular tachycardia (23% to 27%, p <0.01). The median odds ratio for antiarrhythmic prescription was 1.45, indicating that 2 randomly selected hospitals would have had a 45% difference in the odds of treating identical patients with an antiarrhythmic drug. In conclusion, antiarrhythmic drug use, particularly class III antiarrhythmic drugs, is common among ICD recipients at hospital discharge and varies by hospital, suggesting an influence from local treatment patterns. The observed hospital variation suggests a role for augmentation of clinical guidelines regarding the use of antiarrhythmic drugs for patients undergoing implantation of an ICD.