in this study, the impact of capital structure on firms' ownership structure is examined. Therefore, manufacturing firms whose stocks are quoted on the Istanbul Stock Exchange (ISE) over the period 1998 and 2009 are covered using pooled data. On the developed model, it was investigated how ownership structure is affected by the capital structure. According to the reesults of the regression model, it has been found that firms which have less shareholders choose higher-risk capital structures because of increasing firms value. Furthermore, provided that capital intensity becomes higher, firms must hire professional managers. In the instance, professional manager prefer equity financing for preventing financial distressess. In summary, this study concludes that firms' ownership structure affects capital structure.