Pervasive transcription occurs in the human genome to generate thousands of RNA transcripts, and accumulating evidence suggested that the RNA molecules, without protein coding ability, have important roles in diverse biological functions. Long non-coding RNA (lncRNA), with size larger than 200 nt, is a new class of the non-coding RNA that contributes to cancer development and progression. Roles for several lncRNAs in cancers have been characterized and strategies targeting them have inhibitory effects to malignant cells in vitro and in vivo. These findings point to the potential of lncRNAs as prospective novel therapeutic targets in cancers. Recent advance in biological drugs, led by nucleic acid drugs (i.e. siRNAs, antisense oligonucleotides), suggest directions for the development of cancer therapies targeting lncRNAs. Here, we discuss the characteristics of lncRNAs regarding their synthesis, stability and functional role in cells, and emphasize their unique properties that determine their molecular functions. We then discuss the association of lncRNAs with cancers, and illustrate the anticancer effects induced upon modulating the level and function of lncRNAs. We also revisit established methods for targeting RNA molecules and discuss new agents and strategies to attenuate lncRNAs in cancer.