The aim of this study is to analyze the determinant factors of capital structure that examine the firms 'specific factors of capital structure decisions of the sixteen automotive and auto parts industry firms and registered in Istanbul Stock Exchange (ISE), Turkey. This study analyzes the influence of firms' specific variables on capital structure decisions. The firms' annual financial statements for the 2003 to 2006 are obtained from ISE's official web sites and constructed as cross sections data and analyzed with panel data model. The results of this study shows that the capital structure decisions of the automotive and auto parts industry firms are mostly influenced by variables such as return on equity (ROE) and non-debt tax shields. This finding supports with the pecking order theory; which argues that firms' leverage decreases when the profitability is high.