Surviving patients of out-of-hospital ventricular fibrillation (VF) often need rehospitalization after initial hospital discharge, but little is known regarding the frequency of or reasons for rehospitalization. Rehospitalization was examined in 224 patients enrolled in the Cardiac Arrest in Seattle: Conventional Amiodarone Drug Evaluation (CASCADE) study, a randomized clinical trial comparing amiodarone with other antiarrhythmic drug therapy in survivors of out-of-hospital VF. The annual rate of rehospitalization was 79/100 patients/year; 168 of 224 patients (75%) were hospitalized at least once before censoring or cardiac mortality. Baseline left ventricular ejection fraction was significantly lower in patients who were rehospitalized. Rehospitalization rates were lower in patients randomized to amiodarone therapy and in those with the automatic implantable cardioverter-defibrillator, although neither difference was statistically significant. However, length of stay for the first rehospitalization was shorter for patients with automatic implantable cardioverter-defibrillators (p = 0.005). More than 50% of patients were rehospitalized in the first year after enrollment; 65% with ejection fractions < or = 0.3 were rehospitalized in the first year. Rehospitalization was a frequent occurrence for surviving patients of out-of-hospital VF, particularly in those with low ejection fractions.