E. Asarin, O. Maler, P. Caspi, A Kleene Theorem for Timed Automata. In this paper we define timed regular expressions, an extension of regular expressions for specifying sets of dense-time discrete-valued signals. We show that this formalism is equivalent in expressive power to the timed automata of Alur and Dill by providing a translation procedure from expressions to automata and vice versa. The result is extended to omega-regular expressions (Buchi's theorem). [Postscript]