Demonstrating test coverage of requirements is important in regulated business such as health care. Effective test coverage requires not only a well organized testing effort, but also requires testable requirements. Requirements are often reported as not suitable for testing, because they are, for instance, incomplete or too ambiguous.??We describe experience with an approach for creating system test cases using UML use case models and to argue for early steps in requirements engineering to ensure the testability of requirements. We describe a technique that we used to migrate to model based testing by reverse engineering use case models from existing test cases and then regenerating the same test cases back from a use case model.??We describe tool support for this approach (TDE/UML) that allows efficient use of this approach for creation of system tests and our experiences with a Siemens Medical project.