Whole-heart 4D cardiovascular magnetic resonance (CMR) phase-contrast flow measurement enables qualitative and quantitative assessment of intra-cardiac flow. Its feasibility was investigated in 12 pediatric and 13 adult patients with repaired Tetralogy of Fallot (rTOF). Left ventricular (LV) kinetic energy (KE) and pathline-derived flow components were analyzed. KE parameters were significantly correlated with age, but only LV systolic KE remained significantly different after indexing to LV end-diastolic volume. Pediatric rTOF patients had similar LV ejection fraction, indexed LV volumes and mass, but significantly reduced indexed LV systolic KE, retained inflow and increased delayed ejection flow compared with adults.