Absract This study aims to investigate the effect of conditional and unconditional conservatism on the cost of debt of specified companies including 228 listed companies in TSE during 2006 to 2013. The research results indicate that the unconditional conservatism has got a significant relationship with cost of debt.Furthermore the bigger companies have higher financial expenses and more systematic risk and less cost of debt.Financers pay more attention to unconditional conservatism and its consequences on companies.this may be because of intrinsicperformance of conservatism in reducing profit and value of assets.Finally according the research results, managers of the mentioned companies are not interested in implementing conditional conservatism procedures.
