A novel strategy to prepare negatively charged and small DNA-containing liposomes after condensation of plasmid DNA by a cationic lipid in deoxycholate micelle environment is described. The average diameter of resulting complexes was 62 +/- 8 nm. DNA-containing liposomes were then prepared by dialysis. The shape of the resulting liposomes was spherical. The average diameter and the surface charge of the liposomes were 86 +/- 6 nm and -24 +/- 3 mV, respectively. The plasmid DNA inside liposomes remained in a supercoiled form after incubation with DNase.