Automatic Testing with Formal Methods. J. Tretmans, A. Belinfante. In: EuroSTAR'99 - 7th European Int. Conference on Software Testing, Analysis & Review, Nov. 8-12, Barcelona, Spain. EuroStar Conferences, Galway, Ireland, 1999. Also: Technical Report TR-CTIT-17, Centre for Telematics and Information Technology, University of Twente, The Netherlands. The use of formal system specifications makes it possible to automate the derivation of test cases from specifications. This allows to automate the whole testing process, not only the test execution part of it. This paper presents the state of the art and future perspectives in testing based on formal methods. The theory of formal testing is briefly outlined, a test tool is presented which automates both test derivation and test execution "on-the-fly", and an application case study is discussed.