Background. Arrhythmias occurring late after repair of tetralogy of Fallot (TOF) are common. Due to the risk of sudden cardiac death, attention is focused towards ventricular tachycardias (VT). Aim. The aim of this study is the examination of cardiac arrhythmias such as VT in occurring late after repair of TOF. Results. 133 patients, 77men and 56 women, age 1 to 38 years (the average of 20.4 years), were included. 3 patients had arrhythmias. One was atrial flutter (AF). The others were VT. Case 1 was 27 years old man. The radical repair was performed at 3 years old. AF appeared in 10 years after repar. Patch closure and the cryoablation were performed for residual ventricular septal defect and AF at 20 years old. Case 2 was 27 years old man. The radical repair was performed at 4 years old. VT appeared in 15 years after repair. He was observed for Atenolol. Case 3 was 9 years old boy. The radical repair was performed at 2 years old. VT appeared in 6 years after repair. VT disappeared after the catheter ablation. Conclusions. High right ventricular pressure (RVp) was found in 3 patients. No other factors were found in 3 patients. However, all patients with high RVp did not have any arrhythmias. The difference of patients with arrhythmias and without arrhythmias are unknown. We will study the causes of arrhythmias, such as RVp, pulmonary regarditation, operation style and so on.