This paper is to examine the relevance of banarptcy Costs (BC) to Capital Structure with three related purposes: whether or not BC are trival, a proxy methodology for estimating BC, the present value of expected BC vs tax benefits` trade off. For these purposes, the samples includes 19 industrial firms which went bankrupt over period 1970-78 and secondly seven large Companies which went bankrnpt recently in the U.S.  The results are quite strong that BC are not trival. In many cases they exceed 20% of the value of the firm measured just prior to bankruptcy. Direct BC are explicit and administrative costs paid by debtor in reorganization/liqaidation process. Indirect BC are essentially defined as unexpected losses and estimated in two way: a regression method and security analyst`s forcasts.  The present value of expected BC for many of the bankrupt firm is found to exceed the present value of tax benefits from leverage. This implies that firms were overleveraged and that a potentially important ingredient in the discussion of optimum capital structure is indeed the BC factor.  Therefore, BC are relevant to the cost of capital stracture decision and should be considered seriously.