A rapid and simple procedure is described to detect the genomic RNA molecule of Cymbidium mosaic virus (CyMV). This method, named RT-LAMP, allows direct detection of RNA from infected plants without careful RNA extraction, rapid ther-mal cycling and gel electrophoresis. RT-LAMP was successfully used to detect CyMV from leaves of Phalaenopsis orchid in-fected with CyMV. A large amount of byproduct, pyrophospate ion, is produced, yielding a white precipitate of magnesium pyrophosphate in the reaction mixture. The presence or absence of this white precipitate allows easy detection of the amplifi-cation of CyMV genomic RNA without gel electrophoresis.