Large companies like SELEX Sistemi Integrati, consists of several departments (or units), more or less related to each other. In general, every large project is developed by several teams, each team with its own expertise like concurrency, data distribution, etc. These teams may use different UML modeling tools due to their different needs. For example a team may tend to use an open source UML modeling tool like Eclipse, whereas another team may prefer a more stable and consolidated tool like Rational Rose because there are old artifacts (developed with such a tool) that can be reused or because the tool vendor provides a high quality support. Technology changes, this in turn implies that modeling tools evolve and thus the need of the modeling tools users. The life of a large project, like the development of air traffic control system, spans several years. During these years the modeling tools evolve in different versions, providing always more features and hence becoming always more appealing to use. Given the above mentioned circumstances, it is obvious that the interoperability among UML modeling tools is vital to support the development of large projects. With the term interoperability among UML tools we refer to the possibility to develop models and diagrams using a given UML modeling tool, and, in case of absence of any formal error, to be able to evolve theses artifact in another UML modeling tool. The present study reports the solution adopted and the experience gained in SELEX Sistemi Integrati in transferring models and diagrams between Rational Rose 2002 and Artisan Studio 7.