This communication reviews the oil and natural gas resources, reserves and proved reserves of the European Union (EU) and the European Economic Area (EEA). Experts may apply different methodologies and classifications to assess hydrocarbon deposits, which makes their coherent and sound evaluation a challenging task. The analysis presented in this paper shows that there is variation in reported estimates for the EU and EEA oil and gas proved reserves, which is however relatively small; and EEA holds very small and continuously declining shares of world oil and gas proved reserves, about 1.3% and 2.9%, respectively. Nevertheless, conventional reserves and resources and more importantly unconventional gas resources offer a significant potential to increase the European proved reserves. This however requires the proper mapping and assessment of these sources and a rigorous research and development programme for the exploitation of this untapped potential, which could play a significant role in the security of the European energy supply in the years to come. (C) 2010 Elsevier Ltd. All rights reserved.