||This work is examining behaviour of the the company Czech Telecom on the telecommunication market in the Czech Republic. It is trying to find out what competition area it is providing to the other operators, how its behaviour influences these subjects and whether its behaviour enable equal competition conditions. It is described the telecommunication market environment and also is mentioned the historical evolution of antimonopolistic legislation and evolution of the company itself. The main stress is laid on the description of selected cases of the company´s behaviour and the description of related circumstances. In final part is judged its behaviour on the basis of the introduced facts.