Privatization is one of the components of the structural reform program, which aims to achieve higher firm’s performance at the micro level and also achieve higher economic growth, at the macro level. In privatization, the percentage of ownership which transfers from state-owned enterprises to the private sector has always been controversial issues. In this study, first, the data envelopment analysis (DEA) is used to evaluate the performance of listed companies in Tehran Stock Exchange, before and after privatization. Then, the impacts of the percentage of government ownership, on the efficiency of constant and variable returns to scale are evaluated in transferred companies in the Tehran Stock Exchange. The sample consists of 29 transferred companies during the period of 1999-2012. The results show the parameters of state property have a significant negative impact on the performance of companies with constant returns to scale, but in variable returns to scale, the percentage of government ownership does not have any significant effect on the firms' performance.