Over the past few years, Rhone-Poulenc has been relying increasingly on dynamic simulation to design, optimize and operate its production units. Over the course of this period, we have had the opportunity to work with several simulation packages. These have been used to solve a wide range of problems, with respect to the variety of operation units involved and the goals pursued. In this paper, a few applications are presented (control structure design and ;tuning; plant start-up studies, operator training and education). They are used to demonstrate the capabilities and shortcomings of current commercial simulation environments, and to point out the advances that should be done in the future (in terms of solution techniques, model reduction approaches, ergonomics, communication to external software and processes, portability,...).