A large class of systems can be specified and verified by abstracting away from the temporal aspects. In time-critical systems, instead, time issues become essential. Their correctness depends not only on which actions a system can perform but also on their execution time. Due to their importance, time-critical systems have attracted the attention of a considerable number of computer scientists from various research areas.This volume contains the Proceedings of the 3rd International Workshop on Models for Time-Critical Systems (MTCS 2002); MTCS 2002 was held on August 24, 2002 as one of seven satellite workshops co-located with the 13th International Conference on Concurrency Theory (CONCUR 2002), held in Brno (Czech Republic) August 20-23, 2002.The first workshop, MTCS 2000, was held in State College (Pennsylvania, USA) on August 26 2000, co-chaired by Flavio Corradini and Paola Inverardi. while the second workshop, MTCS 2001, was held in Aalborg (Denmark) on August 25, 2001, co-chaired by Flavio Corradini and Walter Vogler. As for the first two workshops, the objectives of MTCS 2002 were (i) to present and discuss promising new proposals on models for time-critical systems, ranging from theory to practice and (ii) to promote interaction between different research areas in the field of time-critical systems. Despite its focus on time-critical systems, MTCS 2002 was also open for time-related issues in general, e.g. performance in systems where time is not critical for the functional behaviour.The papers in this volume were selected for presentation by the Program Committee from submissions received in response to a Call for Papers. Many thanks are due to the members of the Program Committee as well as their sub-referees for their accurate work, and also to the invited speakers P. S. Thiagarajan (Chennai Mathematical Institute) and Walter Vogler (University of Augsburg). We would also like to thank Michael Mislove for his help during the proceedings editorial process and BRICS for the publication of the preliminary proceedings. Finally, our thanks go to Petr Jancar and Mojmir Kretinsky (CONCUR 2002 Conference Chairs) and Antonin Kucera (Workshops Coordinator) for the opportunity they gave us to organize MTCS 2002 and for their support.The papers in this volume were reviewed by the program committee consisting of Rajeev Alur(USA)Jos Baeten(Netherlands)Frank de Boer(Netherlands)Flavio Corradini(Italy)Kim Larsen(Denmark)Gerald Lüttgen(United Kingdom)Jeff Magee(United Kingdom)Andrea Maggiolo-Schettini(Italy)Paul Pettersson(Sweden)Steve Schneider(United Kingdom)Bran Selic(USA)Joseph Sifakis(France)P. S. Thiagarajan(India)Walter Vogler(Germany)A printed version of the current volume was distributed to the participants at the workshop in Brno.April 24, 2003 Walter Vogler, Kim Larsen