International liberalisation and rapid technological development has lead to increased competition in the Nordic telecommunication industry. Increased competition on the telecommunication markets reduces the need for regulation. But will increased competition make Nordic telecommunication markets work efficiently? To answer this question it was decided to establish a working group on the Nordic telecommunication markets at the meeting between the Nordic competition authorities in August 2003. The working group was given the task to describe the Nordic telecommunication markets, analyse the effects of competition in this particular sector, analyse the effect of horizontal and vertical integration on competition in a context of oligopoly, identify barriers to a common Nordic market for telecommunication services, analyse the interplay between competition authorities and regulatory authorities, and consider sector specific regulations’ influence on markets undergoing rapid technological development.