This article focuses on the functioning of OPEC, which was the first attempt at unification of oil extraction and at imposing global control on it. Taking ad - vantage of the considerable demand for energy resources, it was able to exert considerable pressure on the market and even to use the ‘black gold’ as an instrument in the economic struggle faced with unfavourable policy of foreign countries. It seems, however, that the trends in world economy and the constantly improving and more consciously conducted energy policy of importing countries have contributed to the marginalisation of OPEC, which has proven unable to regulate the current excess oil supply crisis on its own. Additionally, the emergence of new players in the market, especially the United States, contributed to the end of ‘oil prosperity’ and transformation of the producer market into a consumer market, where prices are shaped by demand and not as it used to be – by supply. The author further describes the emergence of the organisation in order to present the evolution that took place over almost six decades.