This study is aimed to determine the role of ownership structure on firm performance. Using panel data regression analysis method, the role of variables of ownership structure which includes: ownership concentration, institutional ownership and institutional ownership concentration have been examined for 137 listed firms of Tehran stock exchange within the period 1380 to 1385. It is concluded that ownership concentration doesn’t have any significant effect on firm performance but the effect of two other variables are significant: institutional ownership has positive significant effect on firm performance but the effect of concentrated institutional ownership is negative. In the next part of this research the effect of ownership structure on firm performance based on type of the industry has been studied and it is concluded that the industry factor moderates this effectiveness relationship. The findings of this research shed light on the role of ownership structure plays in corporate performance and thus offer insights to policy makers interested in improving corporate governance system.