This paper، examines the factors that influence energy intensity-the ratio of energy consumption to GDP-in 42 oil exporting and none-oil exporting countries in the period 1985 to 2009. The research applies panel data models to analyze the impacts of oil price، GDP، exchange rate، CO2 emissions، population، surface area and productivity on energy intensity. An attempt is made in this paper، to asses TFP by using DEA software and use both parametric and non-parametric statistics at the same time. The results show in both groups of countries، energy intensity reacts negatively to an increase in GDP and positively to an increase in population and surface area. The results also show that energy intensity responds positively to a hike in Exchange rate in oil producing counties and negatively in non-oil exporting countries.