Aims Many patients with repaired Tetralogy of Fallot (ToF) have right ventricular (RV) volume overload due to pulmonary regurgitation (PR). We studied the effect of volume overload on global and regional RV and left ventricular (LV) deformation, and their relationships with conventional diagnostic parameters. Methods and results In this cross-sectional study, 94 prospectively recruited ToF patients (61% male, age 32.8 +/- 9.5 years, age at repair 1.9 [0.8-5.7] years, 39% pulmonary homograft) and 85 healthy controls of similar age and sex underwent echocardiography and electrocardiography. In a subset of patients, cardiac magnetic resonance imaging, bicycle ergometry, and NT-proBNP measurement were performed within the same day. With speckle-tracking echocardiography, we analysed peak systolic global longitudinal strain (GLS), segmental longitudinal strain and strain rate of the RV free wall, LV lateral wall, and septum. Patients had a lower RV free wall strain than controls (-18.1 +/- 4.5 vs. -26.5 +/- 4.5%, P < 0.001), especially at the apical segment (-15.9 +/- 7.4 vs. -28.2 +/- 7.7%, P, 0.001), and lower RV strain rate. LV GLS was also lower (-17.4 +/- 2.5 vs. -19.6 +/- 1.9%, P < 0.001), mainly due to the interventricular septum. Patients with PR >25% had higher LV GLS and RV free wall strain than patients with PR <= 25% (P = 0.004, P = 0.039, respectively). No relationships were found with NT-proBNP or exercise capacity. Conclusion RV free wall strain and strain rate are decreased in adults late after ToF repair, especially at the apical segment suggesting that apical function is mostaffected in these RVs. Regarding the LV, septal strain is decreased indicating that RV dysfunction adversely affects LV function, probably by mechanical coupling of the ventricles.