<jats:sec><jats:title>Objective</jats:title><jats:p>To compare the elasticity of the main pulmonary artery (MPA) and its branches in fetuses with tetralogy of Fallot (TOF) with that of normal fetuses.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>A prospective study of 42 fetuses with TOF and 84 controls was conducted. The minimum vascular internal diameter in the diastolic period (Dmin) and the maximum diameter in the systolic period (Dmax) of the pulmonary trunk and its branches were measured via M‐mode echocardiography. The strain of the MPA, mid‐left pulmonary artery (MLPA) and mid‐right pulmonary artery (MRPA) was calculated through the formula 100 × (Dmax − Dmin)/Dmin. Correlations between the strain of the pulmonary artery and ventricular function were evaluated in all fetuses with TOF.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The strain of the MPA in fetuses with TOF was significantly lower than that in controls (<jats:italic>P</jats:italic> &lt; .05). Moreover, the strain of the MPA in fetuses with severe TOF was significantly lower than that in fetuses with mild to moderate TOF (<jats:italic>P</jats:italic> &lt; .05). The systolic and diastolic functions of the right ventricle (RV) are impaired in fetuses with TOF. The isovolumic relaxation time (IRT) and myocardial performance index (MPI) of RV were negatively correlated with the strain of the MPA (<jats:italic>r</jats:italic> = −0.452 and −0.261, all <jats:italic>P</jats:italic> &lt; .05), whereas the ejection time (ET) of RV (<jats:italic>r</jats:italic> = 0.286, <jats:italic>P</jats:italic> &lt; .05) was positively correlated with the strain of the MPA in fetuses with TOF.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>The strain of the MPA was obviously decreased in fetuses with TOF during the second and third trimesters of pregnancy. The systolic and diastolic functions of the RV were impaired in fetuses with TOF. The impaired strain of the MPA was correlated with RV function in fetuses with TOF.</jats:p></jats:sec>