A combination of advantages makes it possible to analyse the electrical properties of the Drosophila flight muscles in a more comprehensive way than in any other neuromuscular system. These advantages include large isopotential muscle cells which may be voltage clamped using a two-microelectrode technique, and the ability to selectively isolate the different current-carrying systems by exploiting genetic tools and the developmental properties of the system. Because each current can be studied in isolation from the others, each should be amenable to genetic analysis. Progress has already been made in using mutations to analyse one of these currents, the fast transient potassium current. Combined with the techniques of molecular genetics this system should yield insights into the molecular nature of these channels.