An ideal transgenic gene expression system is inducible, non-leaky, and well tolerated by the target organism. While the former has been satisfactorily realized, leakiness and heavy physiological burden imposed by the existing systems are still prominent hurdles in their successful implementation. Here we describe a new system for non-leaky expression of transgenes in Drosophila. PRExpress is based on a single transgenic construct built from endogenous components, the inducible hsp70 promoter and a multimerized copy of a Polycomb response element (PRE) controlled by epigenetic chromatin regulators of the Polycomb group. We show that this system is non-leaky, rapidly and strongly inducible, and reversible. To make the application of PRExpress user-friendly, we deliver the construct via site-specific integration.