Studies have shown that most of the sequence in the mammalian genome is transcribed into long noncoding RNAs (lncRNAs). Their crucial roles in gene regulation are becoming a hotspot in current biomedical research. LncRNAs can control gene activities through multiple mechanisms such as: 1) direct or indirect regulation of gene expression via cis-/trans-action or function as protein baits in the nucleus; 2) affecting the stability and the translational process of mRNA; 3) functioning as competitors to regulation of microRNA; 4) binding to transcription factors. Recent studies have highlighted the significance of lncRNAs in development and diseases, and their potentials in future clinical application.