Most of analyses for corporate governance have a company with dispersed ownership as a research object. Relevant to this type of company classical conflict „principal-agent“ is decide by traditional mechanisms of corporate governance and mainly by internal mechanisms. A significant number of companies from developing countries have concentrated ownership. Their typical conflicts are between controlling shareholder and minority shareholders (principal-principal), which are reduce by external and internal mechanisms. For the countries of East Europe, incl. Bulgaria, adaptation of market principles is related to entering of foreign capitals and change of shareholders structure. Arise a necessity of researches for corporate governance of companies with concentrated ownership. Traditional issue of corporate governance about protection of rights of minority shareholders has a new dimension – decrease of deviation between right of ownership and right of control