Introduction: Tachyarrhythmia is a well-known cause of reversible left ventricular (LV) dysfunction. LV dysfunction may occur in patients with ventricular arrhythmias. We retrospectively analyzed clinical features and outcomes of patients with reversible LV dysfunction due to ventricular arrhythmias. Methods: Seven consecutive patients with LV dysfunction (ejection fraction (EF) < 35%) underwent catheter ablation for ventricular arrhythmias. Increment of LVEF by 10 % or more after catheter ablation or antiarrhythmic drug treatment was defined as reversible LV dysfunction. Ventricular arrhythmia was mapped conventionally by pacemapping, activation and entrainment mapping. End-point of ablation was non-inducibility of clinical ventricular arrhythmia by programmed ventricular stimulation with/without isoproterenol infusion. Results: Consecutive 5 patients (2 women, age 60짹17 years) with reversible LV dysfunction were identified between March, 2005 and June, 2007. Underlying heart diseases were old myocardial infarction in 1, recent myocardial infarction 1, ischemic heart disease in 1, none in 2 patients. One patient had a cardioverter-defibrillator due to sustained ventricular tachycardia (VT). Premature ventricular complex (PVC), nonsustained ventricular tachycardia (NSVT) and sustained VT were documented in 2, 1 and 2 patients, respectively. Antiarrhythmic drug (1짹1) was ineffective in controlling ventricular arrhythmias. In 4 patients successful catheter ablation was done: PVC from right venricular outflow tract in one, PVC from apicoinferior septum in one, NSVT from left coronary cusp in one, sustained VT after recent inferolateral myocardial infarction in one patient. During follow-up period (7짹7 months), there was no recurrence of clinical arrhythmias in 4 patients. After catheter ablation of ventricular arrhythmias, LVEF improved from 29짹4 to 45짹8 %. Antiarrhythmic drug treatment normalized LV function in one patient after failed ablation. Conclusion: Ventricular arrhythmias can cause reversible ventricular dysfunction. Catheter ablation can improve LV systolic function in selected patients with LV dysfunction due to medically refractory ventricular arrhythmias.