Abstract. We present an approach to automatically generate timeoptimized coverage-based testsuites from a subclass of deterministic statecharts with real-time constraints. The algorithms are implemented as a plugin for a standard UML tool (Poseidon for UML). The statecharts are extended to accomplish common and new coverage criteria inspired by the experience of test experts and translated into timed automata. The model checker UPPAAL then searches a trace with the fastest diagnostic trace option which provides the basis for the testsuite.