||This bachelor thesis focuses on the analyses of the efficiency of crude oil transportation system in the Czech Republic and Slovakia. Several aspects are included from which the amount of transportation tariff and the rate of the diversification of pipeline infrastructure are the most important. Its aim is to determine the oil delivery conditions through Druzhba and IKL pipelines during the years 2008, 2009 and 2010, the development of storage capacity and also the development of attempts to diverse the sources in both states. Firstly, I will outline the history of the formation of oil contractors in order to show the conditions of oil market in the Czech Republic and Slovakia. Secondly, I will analyze the efficiency of the crude oil transportation and compare the Czech and Slovak refineries’ costs for crude oil delivery trough this countries. Finally, this bachelor thesis tries to evaluate the potential sources diversification and measures the position of Druzhba pipeline by means of crude-oil-flows importance.