Imaging of RNA dynamics in living cells is increasingly important to understanding and measuring spatially restricted gene expression. We recently developed a live-cell RNA imaging method that combines an RNA aptamer with a fluorescent chemical probe. The method uses a combination of transfection of a plasmid encoding a gene-specific RNA aptamer with a cell-permeable synthetic small molecule whose fluorescence is restored only when the RNA aptamer hybridizes with its cognitive mRNAs. The versatile method permits the observation of the formation process of stress RNA granules crucial for cellular response to the environment. Simple approaches for simultaneous imaging of multiple RNAs would be essential to gain deeper insights into the functions and dynamics of RNA in cells.