Cardiothoracic area ratio (CTAR), preload index (PLI), ejection fraction (EF), fractional shortening (%FS), and existence of tricuspid regurgitation are now used to evaluate fetal cardiac function. However, assessment of right ventricular function has proved more difficult and challenging than evaluation of left ventricular function, although fetal circulation is right ventricle dominant. The Tei index is an easily measured Doppler-derived measure of left or right ventricular myocardial function. It combines systolic and diastolic ventricular myocardial performance, has been used in circulatory medicine, and now appears appropriate in fetal medicine. Because Tei index is a useful predictor of global cardiac function and is independent of both heart rate and ventricular geometry, it may prove useful in evaluating fetal cardiac function. Previous reports indicate that the normal range the Tei index should be 0.5 or less. In this study, fetuses with recipient fetus in twin-twin transfusion syndrome, hydrops fetalis, and intrauterine growth retardation had high Tei indices associated with fetal right heart failure. These results suggest that the Tei index may prove useful in assessing fetal right ventricle function.