We have carried out a systematic structural study of novel liquid-crystal phases of self-assembled neutral lipid-DNA-metal cation complexes in water solution. Small-angle X-ray scattering experiments have given new insight into the structures of these ternary complexes. We have shown that different divalent metal cations are equally active in promoting the DNA condensation into the ternary complex when different lipid and DNA species are used. In addition, strong indication has been found that the phase of the complexes reflects the structure and symmetry of the parent lipid phase. These achievements provide an important structure-composition correlation that may drive the best design of these materials for future applications as non-viral DNA carriers in gene therapy.