The impact of the Hidden economy on economic indicators such as consumption, production and etc, will necessitate the study of factors affecting this phenomenon to identify and adopt practical solutions to prevent its spread. Studies show that the Hidden economy has been high and factors such as taxes, the size and quality of formal laws and regulations and formal economic performance are the most important factors affecting it.. The main purpose of this paper is to estimate the size of the Hidden economy in the period 1976 to 2010 by the method of MIMIC and its effect on tax revenues. The results show that the Hidden economy allocated a high volume of the country's economy to itself and shows a growing trend in the time period of study. In addition, both size of government and revenue have a significant and positive relationship with the size of the Hidden economy. In addition, the Hidden economy in the long run has a negative and significant impact on tax revenues.