The timing of pulmonary valve replacement in adult patients with repaired tetralogy of Fallot remains controversial. A magnetic resonance imaging study in 17 adult patients with repaired tetralogy of Fallot reveals a statistically significant decrease in right ventricular (RV) volume (RV end-diastolic volume 163 +/- 34 to 107 +/- 26 ml/m2, p <0.001; RV end-systolic volume 109 +/- 27 to 69 +/- 22 ml/m2, p <0.001) at a mean follow-up of 21 months after pulmonary valve replacement; whereas RV systolic function remained unchanged (mean RV ejection fraction 32 +/- 7% to 34 +/- 10%, p = 0.12). In no patients with a RV end-diastolic volume >170 ml/m2 or a RV end-systolic volume >85 ml/m2 before pulmonary valve replacement were RV volumes "normalized" after surgery.