Comprehensive testing of modern communication systems often requires large and complex test suites which then have to be maintained throughout the system life-cycle. Industrial experience, with those written in the standardised Testing and Test Control Notation (TTCN-3), has shown that this maintenance is a non-trivial task and its burden could be reduced if appropriate tool support existed. To this aim, Motorola has collaborated with the University of G?ottingen to develop TRex, a TTCN-3 development environment published under the Eclipse Public License, which notably provides suitable metrics and refactorings to enable the assessment and automatic restructuring of test suites. In this paper we present the TRex tool, which will make it far easier to construct and maintain TTCN-3 tests that are concise and optimally balanced with respect to readability, usability, and maintainability.