We investigated the anisotropic magnetotransport and magnetic properties of (Ga,Mn)As films on GaAs buffer layers grown on Si (001) substrates. The in-plane magnetoresistance (MR) showed similar dependence on the applied magnetic field at 10 K for crystallographically equivalent [110] and [(1) over bar 10] directions. On the other hand, the in-plane MRs for [110] and [100] directions in an as-grown sample were observed to have slightly different magnetic field dependence, which disappeared after low-temperature annealing. The behavior observed in this experiment was different from that observed from (Ga,Mn)As/GaAs systems. This difference was probably related to the competition between uniaxial magnetic anisotropy and cubic magnetic anisotropy induced by the antiphase domains observed for our samples grown on Si (001) substrates. (c) 2006 American Vacuum Society.