Background: Tetralogy of Fallot (TOF) is considered as the most frequent cyanotic congenital heart disorder. Right ventricular (RV) dysfunction is possible to be observed in patients with repaired TOF. Delayed enhancement (DE) is one of the recommended findings for RV dysfunction. Objectives: This study aimed at investigating the DE and its probable relationship with RV function through cardiac magnetic resonance (CMR). Patients and Methods:In this cross-sectional study, the values of cardiovascular magnetic resonance of 110 symptomatic patients, who had repaired TOF for 35 years, were gathered. We compared cardiac function indices (CFI) in patients with and without DE. Results:The patients had an average age of 21.93 ± 6.94 years (59.12% were male and 40.94% were female). 93.66% of the subjects showed DE and 6.44% of them did not have DE. 78.61% of the samples had DE of the right ventricular outflow tract (RVOT); whereas, 21.39% showed DE of the other sites. The differences between mean regurgitation fraction, average RV end-diastolic volume (RVEDV), average RV end systolic volume (ESV), and average RV ejection fraction in DE positive and negative patients were statistically significant (P values = 0.01, 0.04, 0.04, and 0.01, respectively.) Conclusion: DE commonly occurs as a complication of surgery to repair TOF and could be used as a factor for impaired RV function and other complications. Using CMR imaging for follow up of these patients could lead to diagnosis of these complications.