We evaluated the effects of acute preload reduction with inferior vena cava (IVC) occlusion on myocardial velocities during systole (Sa), early (Ea) and late (Aa) diastole, isovolumic contraction (IVV), and myocardial acceleration (IVA) measured by tissue Doppler imaging (TDI) in pediatric patients. A total of 22 patients (5 ± 3 years) were studied: 9 patients (4 ± 3 years) with Kawasaki disease, 8 patients (6 ± 3 years) with atrial septal defect and right ventricular (RV) volume overload, and 5 patients (5 ± 4 years) with pulmonary stenosis and RV pressure overload. Using TDI, Sa, Ea, Aa, IVV were recorded at the base of the RV free wall from a four-chamber view. IVA was calculated by dividing IVV by the time interval from onset of IVV to the time at peak velocity of this wave. In each group, IVC occlusion caused significant decreases in peak Sa, peak Ea, and peak Aa (p < 0.05). However, IVV and IVA did not change during acute preload reduction. This study demonstrated the effects of acute preload reduction on TDI velocities. In contrast to peak Sa, peak Ea, and peak Aa, IVV and IVA were unaffected by preload within a physiological range.