This paper evaluates the threshold effect of income on carbon dioxide emissions intensity in the MENA countries using panel smooth transition regression model. For this purpose, the variables of financial development, openness, energy intensity, income per capital and carbon dioxide emissions intensity over the period 1980 to 2011 are employed. While the results strongly indicated the existence of a nonlinear relationship, considering one transition function and two threshold parameters is sufficient to specification of nonlinear relationship among variables. The empirical results show that the slope parameter in which the speed of adjustment represent from one regime to another one is estimated equivalent of 78762, and two threshold parameters estimated 1176 $ and 11614 $ based on income per capita respectively. The variables of openness and income per capital lead to reduce carbon dioxide emissions intensity in both regimes in which the impact of income per capital in first regime and openness in second regime is greater than another regime. Although, financial development leads to slight increase in carbon dioxide emissions intensity in the first regime, but in the second regime leads to decreases it.