BACKGROUND In patients with low ejection fraction and ventricular dyssynchrony, cardiac resynchronization therapy (CRT) is an accepted therapeutic modality. In these patients, CRT can improve the quality of life and exercise tolerance in addition to improved survival. On the other hand, antiarrhythmic effects of CRT is a place of debate. METHOD In this study, we evaluated the effect of CRT-induced reverse remodeling on ventricular arrhythmia in heart failure patients. Patients with CRT were divided to two groups of responders and nonresponders. Responders were those with reduction of LVESD of more than 10% or increase in LVEF of more than 5%. They were visited and device analysis was performed during the follow-up. RESULTS One hundred and nineteen patients were enrolled in this study. Those with reverse remodeling experienced fewer ventricular arrhythmias after two years of follow-up (N = 2 vs 11, P = 0.001). CONCLUSION Reverse remodeling associated with CRT implantation can result in decreased frequency of ventricular arrhythmias.