As regards carbon dioxide emissions are the major cause of climate change for numerous, study on the factors affecting its emissions have a high significance. This study focuses on the relationship between co2 emissions and GDP, population growth, openness and energy consumption, which inclusive a wider range of factors affecting on co2 emissions will be examined. For this purpose, long-term and short-term relationship between co2 emissions and other variables is estimated and analyzed with utilizing ARDL model for annual data from 1972 to 2011.The results of this study indicate that all variables except for openness, have a positive impact on co2 emissions, while openness has a negative effect on co2 emissions.