The ryanodine receptor (RYR) genes encode evolutionarily conserved calcium release channels involved in a wide range of calcium-dependent biological processes. Here we show that the sole Drosophila RYR gene (dRyR) functions in differentiated somatic and cardiac muscle as well as in developing embryonic myotubes. In the larval body wall muscles, dRyR protein localizes at the SR membranes and dRyR knockdown adversely affects muscle contractility, suggesting its conserved role in calcium-triggered