The invention provides for double stranded nucleic acid molecules comprising a 5′； extension of the sense or antisense strand and further comprising a plurality of nucleotides that are conjugated to a ligand and methods of using the double-stranded nucleic acid molecules. Ligand-modified oligomers where the sense stands form a tetraloop provide new potent and stable RNA interference agents. These dsNA molecules are synthesized using a plurality of nucleotides that include ligand-modified monomers, nucleotide analog monomers, modified nucleotide monomers and the like, using standard nucleotide synthetic methods and systems.
