The use of formal specifications in software development allows the use of certain automated tools during the specification and software development process. Formal description techniques have been developed for the specification of communication protocols and services. This paper describes the partial automation of the protocol implementation process based on a formal specification of the protocol to be implemented. An implementation strategy and a related software structure for the implementation of state transition oriented specifications is presented. Its application is demonstrated with a much simplified Transport protocol. The automated translation of specifications into implementation code in a high-level language is also discussed. A semiautomated implementation strategy is explained which highlights several refinement steps, part of which are automated, which lead from a formal protocol specifieation to an implementation. Experience with several full implementations of the OSI Transport protocol is described.