This study investigated the major factors that influence the CO2 emission in 12 Middle Eastern countries, namely, Bahrain, Egypt, Iran, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syria, the UAE, and Yemen. A panel model was used in this study and the period 1990-2009 was considered. The results showed that the total primary energy consumption, foreign direct investment net inflows, GDP, and total trade were important factors in increasing CO2 emission in the investigated countries. Thus, it is important for these counties to examine the requirements for foreign investment to promote environmental protection and increase the technological transfer through foreign companies to reduce the environmental damage. It is also important for them to adopt trade-related measures and policies to increase environmental protection since total trade increases CO2 emission. It is also crucial for these countries to increase energy productivity to achieve their GDP growth. (c) 2012 Elsevier Ltd. All rights reserved.