Cardiac sarcoidosis (CS) is frequently complicated by fatal ventricular arrhythmias. T-peak to T-end interval to QT interval ratio (TpTe/QT) on electrocardiograms (ECG) was proposed as a marker of ventricular repolarization dispersion. Although this ratio could be associated with the incidence of ventricular arrhythmias in cardiovascular diseases, its prognostic implication in patients with CS is unclear. We sought to investigate whether TpTe/QT was associated with long-term clinical outcomes in patients with CS. Ninety consecutive patients with CS in 2 tertiary hospitals who had ECG data before initiation of immunosuppressive therapy between November 1995 and March 2019 were examined. The primary outcome was a composite of advanced atrioventricular block, ventricular tachycardia or ventricular fibrillation (VT/VF), heart failure hospitalization, and all-cause death. During a median follow-up period of 4.70 (interquartile range 2.06-7.23) years, the primary outcome occurred in 21 patients (23.3%). Survival analyses revealed that the primary outcome (p < 0.001), especially VT/VF or sudden cardiac death (p = 0.002), occurred more frequently in patients with higher TpTe/QT (≥ 0.242, the median) than in those with lower TpTe/QT. Multivariable Cox regression analysis showed that a higher TpTe/QT was independently associated with increased subsequent risk of adverse events (hazard ratio1.11, 95% confidence interval 1.03-1.20, p = 0.008) even after adjustment for the significant covariates. In conclusion, a higher TpTe/QT was associated with worse long-term clinical outcomes, especially fatal ventricular arrhythmic events, in patients with cardiac sarcoidosis, suggesting the importance of assessing TpTe/QT as a surrogate for risk stratification in these patients.