Ventricular septal defects (VSDs) have recently demonstrated poorer functional outcome with disrupted ventricular contractility during exercise in young patients. It is not known whether this will change with age. Therefore, echocardiography was performed in older patients with congenital VSDs, either surgically closed or unrepaired and all without Eisenmenger physiology, to compare functional outcomes with healthy peers. Transthoracic echocardiography was performed at rest and during supine bicycle exercise, with tissue velocity Doppler for assessment of primary end points: isovolumetric acceleration and systolic velocities. In total, 30 surgically closed VSDs (51 ± 8 years) with 30 healthy controls (52 ± 9 years) and 30 unrepaired VSDs (55 ± 12 years) with 30 matched controls (55 ± 10 years) were included. Surgical patients displayed lower right ventricular (RV) systolic and early diastolic-filling velocities compared with controls, p <0.01, lower tricuspid annular plane systolic excursion (17.8 ± 5 vs 22.7 ± 3mm, p <0.01) and lower fractional area change (37.8 ± 6 vs 46.4% ± 7%, p <0.01). Unrepaired VSDs also had lower RV fractional area change than matched controls (39.9 ± 7 vs 48.4% ± 7%, p <0.01). Both patient groups had more tricuspid regurgitation and larger RV outflow tract dimensions than controls, p <0.01. During exercise, isovolumetric acceleration and systolic velocities were lower in both patient groups compared with controls, with the difference increasing with workload level. In conclusion, adults in their mid-50s with surgically closed or unrepaired VSDs have abnormal RV function at rest, with even more pronounced differences during exercise. These results suggest that a VSD, whether repaired early or considered hemodynamically insignificant, is not a benign lesion and continuous follow-up of adults is warranted.