The aim of this study is to explore the determinants of the capital structure in Joint Stock Companies that subject to the supervision of Syrian Commission on Financial Markets and Securities, focusing on the period (2007-2011). The research try to explore whether the decision of the firms concerning the financial leverage is in conformity with the patterns proclaimed in previous studies. The study summarized the relation between the accountancy indicators and financial structure of the Joint Stock Companies in Syria by using multi-regression analysis. The study included the following independent variables: size; age; profitability; volatility; liquidity; growth prospects; tangibility; ownership structure; and taxes. On the other hand, the leverage ratio represented the variable related to the company’s financial structure. The study concluded that the leverage ratio in the Syrian companies is about (48%). In addition, the study concluded a statistically significant positive relationship (at 5% significance level) between the financial structure of Syrian companies and all of the company's size; profitability; and ownership structure. The study also found that there is a significant negative relationship (at 5% significance level) between the financial structure of Syrian companies and all of the company's volatility; liquidity; and tangibility. Finally, no evidence has been provided by the study about the relationship between financial structure and all of the company's life; the expected growth; and the company's tax.