In this paper a macroeconomic approach is derived to develop a long run electricity demand model to analyze the main factors affecting electricity demand in the Islamic Republic of Iran. According to the definition of a demand function, electricity demand, in general, is determined by some main factors including gross domestic product (GDP), prices, etc. This paper, by analyzing the specific political and economical conditions in the Iran, introduces electricity intensity and a dummy variable WAR into the electricity demand forecasting model. A binary dummy variable, WAR is applied to correct the model (between the years 1980-1988 during the Iran and Iraq war). In this study, two popular econometric techniques namely unit root test and cointegration model is derived for modeling the electricity demand. Cointegration is established between kWh and, respectively, GDP, electricity price, electricity intensity, and WAR as a dummy variable. The results show that although GDP is still the most important factor for electricity demand, electricity demand is negatively related to efficiency improvement and tariffs in Iran.