Abstract: The invention provides a method for determining whether a test compound binds to a target RNA, the method comprising the steps of: (a) contacting the test compound with a pair of indicator molecules comprising an antimicrobial labelled with a donor group or an acceptor group and the target RNA labelled with a complementary acceptor or donor group, the pair being capable of binding to each other in an orientation that permits the donor group to come into sufficient proximity to the acceptor group to permit fluorescent resonance energy transfer and/or quenching to take place; and (b) measuring the fluorescence of the target RNA and/or the antimicrobial in the presence of the test compound and comparing this value to the fluorescence of a standard.