Telecommunication markets are a valuable factor that contributes to the economic growth and development. The development of the telecommunication markets and services was slower in the countries in transition than in developed European countries, altough after the fall of communism countries in transition implemented a big progress in spreading and modernizing of their telecommunication network.The paper analysis the level of concentration of telecommunication industry in Croatia from 2003 to 2008. The data used in the analysis consider 50 Croatian largest IT firms that are operating on telecommunication market and specific telecommunication sectors: producers of telecommunication equipment, distributers of telecommunication services and im...