The fate of functional tricuspid regurgitation (TR) after closure of a secundum atrial septal defect (ASD) without any corrective tricuspid valve (TV) surgery remains unclear. We investigated this and the predictors of persistent TR after ASD closure. Thirty-two consecutive patients with moderate or severe TR before ASD closure were examined. Of these, 23 underwent percutaneous ASD closure, and 9 underwent isolated surgical ASD closure. The left ventricular end-diastolic volume, left ventricular ejection fraction, right ventricular end-diastolic area, right ventricular fractional area change, right ventricular spherical index, right atrial area, TV annular diameter, TV tethering height, pulmonary artery systolic pressure, and pulmonary/systemic blood flow ratio were determined by echocardiography before and early after ASD closure. The color Doppler maximal jet area was used to assess the severity of TR. After ASD closure, the jet area decreased for all patients (p = 0.009); however, 16 patients (50%) had persistent TR. Multivariate analysis revealed that only pulmonary artery systolic pressure before ASD closure was related to the TR jet area after ASD closure (p = 0.003). A pulmonary artery systolic pressure of >60 mm Hg predicted persistent TR with 100% sensitivity and 63% specificity. In conclusion, functional TR was ameliorated after percutaneous and isolated surgical ASD closure, although persistent TR was common. The presence of pulmonary hypertension before ASD closure predicted persistent TR; therefore, corrective TV surgery should be considered at ASD closure in adult patients with moderate or severe TR and concomitant pulmonary hypertension.