Aim: The aim of this study was to demonstrate the changes of right and left myocardial performance indices (MPI) in small-for-gestational age (SGA) fetuses during 28-40 weeks of gestation. Material and Methods: Singleton pregnant women during 28-40 weeks of gestation were enrolled. Estimated fetal weight was used to classify the subjects into appropriate-for-gestational age (AGA) and SGA groups. The Doppler indices of umbilical and middle cerebral arteries, including amniotic fluid index, were used to distinguish constitutional SGA (both normal Doppler indices and amniotic fluid index) from intrauterine growth restriction (IUGR) fetuses (abnormal Doppler indices and/or oligohydramnios). MPI was obtained and compared between the groups. Inter-and intra-observer variations were also assessed. Results: Fifty women had AGA fetuses whereas another 50 cases had SGA fetuses (41 constitutional SGA and nine IUGR). Right MPI in AGA fetuses was constant whereas left MPI was slightly increased. The MPI of SGA fetuses were significantly greater than those of AGA fetuses starting from 30 weeks gestation until delivery (P < 0.01 and <0.05 in right and left side, respectively). Subgroup analysis demonstrated right and left MPI of IUGR fetuses increased with advancing gestation and were significantly greater than those of constitutional SGA and AGA fetuses, which appeared to be similar. The reproducibility of the test was high. Conclusions: In SGA fetuses, the MPI of right and left ventricles was significantly increased with advancing gestation compared to AGA cases.