Locked nucleic acid (LNA) is a novel oligonucleotide analogue in which 2'-O and 4'-C positions in the b-D-ribofuranosyl ring are joined via an O-methylene, S-methylene or amino-methylene moiety, locked in a C3'-endol3E north (N)-type furanose conformation. LNAs posses many properties, such as extraordinarily high hybridize affinities for complementary DNA/RNA sequences, remarkable antisense activity, nuclease resistance, good aqueous solubility and none detactable toxicity, et al. LNAs is a most promising molecule for development of diagnostics and therapeutics. For example, apply LNAs to single--nucleotide polymorphisms genotyping, telomerase activity have been efficiently suppressed by LNA oligomers, efficient cleavage of highly structured RNA has been achieved using LNA-modified DNAzymes (LNAzymes), and so on.