One aspect of the present invention relates to a double-stranded oligonucleotide comprising at least one ligand. In certain embodiments, a ligand is bound to only one of the two oligonucleotide strands comprising the double-stranded oligonucleotide. In certain embodiments, both of the oligonucleotide strands of the double-stranded oligonucleotide independently comprise a bound ligand. In certain embodiments, the oligonucleotide strands comprise at least one modified sugar moiety. In certain embodiments, a phosphate linkage in one or both of the strands of the oligonucleotide has been replaced with a phosphorothioate or phosphorodithioate linkage. In a preferred embodiment, the ligand is cholesterol or 5β-cholanic acid. Another aspect of the present invention relates to a single-stranded oligonucleotide comprising at least one ligand. In certain embodiments, the oligonucleotide comprises at least one modified sugar moiety. In certain embodiments, a phosphate linkage of the oligonucleotide has been replaced with a phosphorothioate or phosphorodithioate linkage. In a preferred embodiment, the ligand is cholesterol or 5β-cholanic acid. The ligand improves the pharmacokinetic properties of the oligonucleotide.