A brief review on use of fossil fuel resources and sustainability is given in this paper. A sustainability index for fossil fuels is developed, which aims to determine the most efficient management of fossil fuel resources for the energy system. The study is conducted for 62 countries, in the presence of independence, lifetime and environmental constraints. The effect of these indicators are then integrated into a single index for oil, natural gas, and coal. Two approaches have been taken. The first one employs equally weighing of each index, where the second one weighs the indices by using principle component analysis. It is concluded that Fossil Fuel Sustainability Index (FFSI) values indicate that countries supporting oil as the one and only major player are condemmed to suffer due to incompetent energy policies. (c) 2006 Elsevier Ltd. All rights reserved.