This study aimed to compare respiratory variation in transthoracic echo-derived aortic blood flow velocity (∆Vpeak) and inferior vena cava diameter (∆IVCD) with central venous pressure (CVP) as predictors of fluid responsiveness in children after repair of ventricular septal defect (VSD). A prospective study conducted in pediatric intensive care unit investigated 21 mechanically ventilated children who had undergone repair of VSD. Standardized volume replacement (VR) was the intervention used. Hemodynamic measurements including CVP, heart rate, mean arterial pressure, transthoracic echo-derived stroke volume (SV), cardiac output, ∆Vpeak, and ∆IVCD were performed 1 h after patient arrival in the intensive care unit. Hemodynamic measurements were repeated 10 min after VR by an infusion of 6% hydroxyethyl starch 130/0.4 (10 ml/kg) over 20 min. The volume-induced increase in the SV was 15% or more in 11 patients (responders) and less than 15% in 10 patients (nonresponders). Before volume replacement, the ∆Vpeak (23.1 ± 5.7% vs. 14.0 ± 7.7%; p = 0.006) and ∆IVCD (26.5 ± 16.2% vs. 9.2 ± 9.1%; p = 0.008) was higher in the responders than in the nonresponders, whereas CVP did not significantly differ between the two groups. The prediction of fluid responsiveness was higher with the ΔVpeak, as shown by a receiver operating characteristic curve area of 0.83 (95% confidence interval [CI], 0.61-1.00; p = 0.01), a ΔIVCD of 0.85 (95% CI, 0.69-1.00; p = 0.01), and a CVP of 0.48 (95% CI, 0.22-0.73; nonsignificant difference). The ∆Vpeak and ∆IVCD measured by transthoracic echocardiography can predict the response of SV after volume expansion in mechanically ventilated children at completion of VSD repair.