Our purpose is to make a contribution to parallel programming in an asynchronous context, according to distributed architectures. The main difficulty in inventing parallel programs is to specify the way parallel components do cooperate. These features have to be progressively derived as systematically as possible from abstract specifications. The challenge is then to introduce relevant expression tools and a convenient parallel modeling for such developments. Programming with equations seems to be a very convenient way for that purpose. The aim of this paper is to associate an asynchronous parallel interpretation with fix-point systems, in which communications are defined.