A multivalent cationic lipid having a positively-charged head group including two quaternary amine groups and a hydrophobic portion including four hydrocarbon chains, which may be the same or different and which are optionally substituted alkyl and alkenyl groups, two alkyl chains attached to each of the two quaternary amine groups can be used for the introduction of polyanionic materials such a nucleic acid polymers into cells. Specific cationic lipids are N,N,N',N'-tetraoleyl-N-N'-dimethyl-1,3-propanediammonium chloride and N,N,N',N'-tetraoleyl-N-N'-dimethyl-1,6-hexanediammonium chloride.