This paper studies the effect of corporate governance and audit quality on the debt cost financing of Tunisian listed companies. When, banks and other financial institutions dont participate in corporate governance structures (such as boards of directors for example), they might pay attention to overall quality of monitoring tool set up within companies and to financial reportings quality. So, we may expect an inverse relation between the debt cost and the quality of governance and auditing structure. Using a pooled sample of large, nonfinancial listed Tunisian companies over the years 2000 to 2011, the empirical findings reveal that corporate governance quality has a significant reducing effect on the cost of debt, whereas audit quality does not. Specifically, multivariate analyzes document an inverse relation between the ex post cost of debt and (1) the Board size, (2) the part of independent directors, (3) the presence of institutional shareholders, and (4) the international auditor network membership. Key Words: Audit quality ? governance ? board - Monitoring ? Debt cost ? Tunisian listed companies.