The purpose of this research is to test the main theories of firm debt maturity in an emerging economy, including agency conflict; signaling and tax theories. This paper investigates the firm specific determinants of debt maturity structure for a sample of 140 Iranian manufacturing firms listed in Tehran Stock Exchange during the period 2001 to 2009. Employing random effect panel data analysis, and multivariate regression, the study provides empirical evidence that profitability, firm size, tangibility, growth opportunity and financial leverage have significant effects on debt maturity choice in Iranian context however; tax effects and business risk are not significantly related to the debt maturity structure. Key words: Debt maturity structure, profitability, dividend policy, business risk.