Using synchrotron small angle X-ray scattering and energy dispersive X-ray diffraction, we have found that cationic liposomes made of the monovalent cationic lipid, 3-[N-(N,N-dimethylaminoethane)-carbamoyl]cholesterol (DC-Chol) and the neutral lipid dioleoylphosphatidylethanolamine (DOPE) condense DNA molecules forming complexes (DC-Chol/DOPE-DNA) which are not assembled in an inverted hexagonal structure as recently reported, but, conversely, form a well-ordered lamellar liquid-crystalline phase with distinct regimes of DNA packing density. (c) 2005 Elsevier B.V. All rights reserved.