摘要：With numerous advancements in novel biochemical techniques, our knowledge of the role of RNAs in the regulation of cellular physiology and pathology has grown significantly over the past several decades. Nevertheless, detailed information regarding RNA processing, trafficking, and localization in living cells has been lacking due to technical limitations in imaging single RNA transcripts in living cells with high spatial and temporal resolution. In this review, we discuss tech- niques that have shown great promise for single RNA imaging, followed by highlights in our recent work in the development of molecular beacons （MBs）, a class of nanoscale oligonucleotide-probes, for detecting individual RNA transcripts in living cells. With further refinement of MB design and development of more sophisticated fluorescence microscopy techniques, we envision that MB-based approaches could promote new discoveries of RNA functions and activities.