We study ground state phase diagrams for the MMX chains, using a one-dimensional dimerized 3/4-filled extended Hubbard-Peierls model with sire diagonal and off-diagonal electron-lattice interactions. The ground states no obtained mainly in the Hartree-Fock approximation, and their accuracy is checked by the exact diagonalization of small clusters. We find a new phase in addition to Frequently considered phases and compare our results with experimental results.