The present invention provides iRNA agents comprising at least one subunit of the formula (I): wherein: A and B are each independently for each occurrence O, N(RN) or S； X and Y are each independently for each occurrence H, OH, a hydroxyl protecting group, a phosphate group, a phosphodiester group, an activated phosphate group, an activated phosphite group, a phosphoramidite, a solid support,-P(Z')(Z")0- nucleoside, -P(Z')(Z")O-oligonucleotide, a lipid, a PEG, a steroid, a lipophile, a polymer, -P(Z')(Z")O-Linker-OP(Z''')(Z'''')O-oligonucleotide, a nucleotide, an oligonucleotide, - P(Z')(Z")-formula(I), -P(Z')(Z")- or -Linker-R； R is LG, -Linker-LG, or has the structure shown below: LG is independently for each occurrence a carbohydrate, e.g., monosaccharide, disaccharide, trisaccharide, tetrasaccharide, oligosaccharide, polysaccharide； RN is independently for each occurrernce H, methyl, ethyl, propyl, isopropyl,butyl, or benzyl； and Z', Z", Z''' and Z" are each independently for each occurrence O or S.
