Epitaxial MnF2 layers were grown on CaF2/Si(lll) substrates using molecular beam epitaxy. Layer-by-layer growth was observed at room temperature. The first three molecular layers of MnF2 have cubic fluorite lattice inherited from CaF2. Thicker layers have tetragonal lattice of rutile with (110) plane parallel to the substarte surface and [001] axis along [110] directions of CaF2. Thus there are three orientations of rotational domains in the MnF2 layer. At a temperature higher than 400 degrees C, nucleation begins with three-dimensional clusters which are aligned with respect to steps on CaF2 surface. After coalescence of the clusters, single domain film can be obtained.