A common problem in UML-based development is to verify whether a given model behaves as required. In particular it is difficult to understand whether the model of a real-time system satisfies the given time constraints. In general the problem is that the real performances of a system can be evaluated only after its implementation. An effective way of tackling this problem consists in simulating the execution of the model, observing its behavior and comparing it with the user requirements. This article describes a procedure for converting a given UML model into an equivalent model that can be simulated by means of a commercial environment.