Background: Patients with Brugada syndrome (BRS) have a shorter ventricular fibrillation cycle length (VFCL) than patients with a structural heart disease. Object: The aim of this study was to reveal the differences in the VFCL between patients with asymptomatic BRS and those with symptomatic BRS. Method: This study included 21 patients (21 men; age 53.4±3.4 years) who received implantable cardioverter defibrillators (ICDs) between April 2005 and December 2010. Among these patients, 16 patients did not have ventricular arrhythmia (asymptomatic group), while 5 had ventricular arrhythmia (symptomatic group). We examined the cycle length of the ventricular fibrillation that was induced by extra-stimulation from right ventricular and T wave shock. Results: Patients with symptomatic BRS had a significantly shorter VFCL than those with asymptomatic BRS; the ventricular fibrillation had been induced by extra-stimulation form the right ventricular apex (147.2±15.4 ms vs 178.5±3.2 ms, P=0.0062) and the right ventricular outflow tract (153.6±8.9 ms vs 180.7±3.9 ms, P=0.0106), and by T wave shock from the ICDs (162±8.6 msec vs 193.9±2.9 ms, P=0.0003). Conclusion: The estimation of VFCL may be useful for the risk stratification of patients with BRS.