The impact of long-term financing on the company’s return level is among the topics of interest to both creditors and investors. Therefore, this study aims to investigate this issue by examining a sample of companies listed on the Tehran Stock Exchange during the years 2005 to 2011, focusing on the financial leverage effect on the company’s return. Of course, in order to achieve suitable results, the two groups of debt have been categorized based on the ratio of debt to total assets. The findings indicate that companies which finance a larger portion of their financial resources through long-term borrowing and have higher financial leverage, experience a return that is proportional to the level of risk endured. However, as the amount of long-term debt increases, this return decreases. In companies with fewer loan facilities, there is no meaningful relationship between return and total debt ratio.