Privatization is an executive, financial and legal process, which the governments in many countries of the world benefit for the purpose of effecting reforms in the country's economy and administrative system. The present research is aimed at evaluation of the effect of privatization on the function of companies transferred to private and public sector in Iran so as to study the optimized function of companies during the period after transfer against the period before transfer and the effect of structure of various ownerships ( private and public) on the function of transferred companies during the period after transfer. This study will also help us to specify which kind of private or public ownership has been more effective during the period after transfer. Using the financial information of 18 companies(8 companies transferred to the private sector and 10 companies transferred to semi-governmental sector), which were transferred during the years 1991 through 2000, the performance related to three years before and after transfer of companies of the said two groups was studied. The results of testing hypotheses show that although the performance of companies has developed after their transfer, but there is no meaningful statistical difference between the companies' performance before and their transfer. Also there is no meaningful difference between the performance of companies transferred to the public and private sectors during the period after transfer.
)