We present a system level description mechanism based on UML-notations from which one can automatically extract SystemC code. Our modelling framework is based on a restricted set of UML diagram types and some standard extensions influenced by the communication infrastructure of SystemC. The system specifications are developed using the UML-compatible tool, Rhapsody. We then translate the internal representation of the design generated by Rhapsody into SystemC code. The extensions we have implemented using the stereotype feature of the Rhapsody tool pull up the communication infrastructure and timing feaures of SystemC to the UML-level. Consequently, we can describe executable platforms at the UML-level as well as translate UML-based application descriptions to SystemC level.