Long non-coding RNAs (lncRNAs) play important roles in cancer. They are involved in chromatin remodeling, as well as transcriptional and post-transcriptional regulation, through a vari-ety of chromatin-based mechanisms and via cross-talk with other RNA species. lncRNAs can func-tion as decoys, scaffolds, and enhancer RNAs. This review summarizes the characteristics of lncRNAs, including their roles, functions, and working mechanisms, describes methods for identi-fying and annotating lncRNAs, and discusses future opportunities for lncRNA-based therapies using antisense oligonucleotides.