International Science Community Association Research Journal of Recent Sciences 2277 - 2502 4 1 2015 January 2 The Investigation of the Effective Factors upon the Capital Structure of the accepted Companies in Tehran Stock Exchange 68 72 EN Mehdi Yousefi 1 Department of Biology, Payam Noor University, Tehran, IRAN Sanaz Toranj 2 SeyedEmad Hosseini 1 ³ Deputy Director of Research, Institute for International Energy Studies (IIES), IRAN Abbasi² Farshad 2 Department of Engineering, Islamic Azad University, Marivan Branch, IRAN AhmadFarmahini Farahani 3 Director of Research, Institute for International Energy Studies (IIES), TEHRAN, IRAN Alidade Bahareh 1 Department of Industrial Engineering, Zahedan Branch, Islamic Azad University, Zahedan, IRAN Mohammad Ghasemi 2 Assistant professor, Department of Agricultural Economics, University of Zabol, Zabol, IRAN Rafiezadeh Mojtaba 1 Department of Management, Rasht Branch, Islamic Azad University, Rasht, Iran Badri Abassi 2 Mehrdad Godarzv 3 Chegini 4 Alinezhad Amin 1 Department of Studies in Linguistics, University of Mysore, INDIA Alipour Mohammad 1 Department of English, Khorasgan Branch, Islamic Azad University (IAU), Isfahan, IRAN Reza HaghverdiHamid 2 Biria Reza 3 ForoughiAbari1 Afsaneh 1 Department of English, Khorasgan Branch, Islamic Azad University, Isfahan, IRAN AhmadReza Lotfi 2 MuhammadIrfan Khattak 1 University of Engineering and Technology Peshawar, PAKISTAN J. Ma 2 School of Electronic, Electrical and Systems Engineering, Loughborough University, UK Shafi Muhammad 3 Faculty of Computer Science and Engineering, GIKI Topi, PAKISTAN Mohammad Saleem 4 Garde A.S. 1 Bire Sarang 1 School of Mechanical and Building Sciences, VIT University, Vellore, Tamilnadu 623014, INDIA Thube Yogesh 2 Arefeh Mohaghegh 1 Department of Accounting, Semnan branch, Islamic Azad University, Semnan, IRAN > Research Paper 2014 2 16 2015 January 2 Purpose – This study tries to help the senior financial managers to provide optimal capital structure and among different interior factors, focus their attention to profitability trend. Design/methodology/approach–The research design is comparative- deductive and according to the research and nature of the variables, is a practical research and methodologically is a comparative- analyzing and also a kind of case study. Findings – The results of the research indicate that, profitability is the only effective variable on the capital structure of companies in Iran, and the other factors are ineffective. According to these results, the companies which have higher profitability use more debt in their capital structure. And companies with lower profitability don’t have a good chance in financing through debt. The research's results indicate that the capital structure of different groups of companies in stock exchange is different. Research limitations/implications – The paper is limited to a comparative- deductive study that may have further implication for research such as: -Presenting one pattern for determining the companies optimal capital structure. -The reason of changes in capital structure of companies during their life. Originality/value – Since Capital structure or in other words, the combination of financial resources and its effective factors are every company's basic issues which should be considered by senior managers, especially financial managers, Investigation of the effective factors can also be practically and theoretically beneficial in Iran. Copyright@ International Science Community Association