The article considers the criteria of English business discourse effectiveness. The object of the research includes samples of monologic and dialogic English business discourse, illustrating the effective and ineffective communication in oral and written speech. The subject of the research is functional and pragmatic properties of business discourse aimed at effective business communication, defining the criteria of the concept of efficiency. The importance of this topic is determined by high demand for effective means of communicative influence. The author stresses that emerging communicative technologies require more attention both at the level of understanding and identification. The author offers the method of evaluation of discourse effectiveness from the dynamic and systemic point of view - with the help of functional synergetic analysis. She defines the way how the unity of discourse meanings organised in an orderly system affects the consciousness of business partners. The research lets us claim that today successful speech communication is understood as interaction beneficial for both parties, preserving the business relationship balance and corresponding to mutually set goals. The article shows that in order to communicate effectively the addressee has to possess a wide range of pragmatic means of influence on which the result of talks, presentations and transactions depend. The practical result of speech activity is preconditioned by the choice of speech expression form which is made in business communication in the process of speech planning determined by communicative situation and intentions of speakers.