From 1965 to 1984, 279 patients with tetralogy of Fallot underwent corrective surgery at Niigata University Hospital, and 228 patients were closely followed postoperatively. Late deaths occurred in 12 cases (5.3%), and overall event-free rate at 20 years postoperatively was 76.9%. The most common events were heart failure due to residual cardiac anomaly and symptomatic ventricular arrhythmias. Treadmill test by Ellestad protocol was performed on 74 postoperative patients, 49% of whom could not complete the protocol. These patients had higher RVEDP and lower RVEF than completing patients. Holter ECG was done on 48 long-term postoperative patients, 48% of whom showed complex ventricular arrhythmias. The age at operation was older and postoperative elapsed time was longer in patients with complex ventricular arrhythmias. Although most postoperative TF patients are able to enjoy a normal social life, the treadmill test and Holter ECG revealed that many patients had latent RV dysfunction and complex ventricular arrhythmias with or without significant symptoms. Since the number of symptomatic patients increases after 15 years postoperatively, a regular check-up with cautious observation is important for the patients' care.