The purpose of this research is to study the fetal heart biomechanics during cardiac cycle. A 3D FEM of the human fetal heart (FH) is built by using the geometry and the ¯ber orientation measurements of a post-mortem FH. An anisotropic hyperelastic constitutive law describing the mechanical properties of the active myocardium is used. Kinematics of the heart and ejection fraction predicted by the model are compared with experimental observations. Our model can quantify the transmural distribution of strains and stresses during the cardiac cycle. Several authors supported the idea that fetal growth depends on the mean wall stress averaged through the space and during the cardiac cycle. For this reason, the results obtained in this work can be relevant in order to better understand the human FH growth process.