This study examines the impact of the Sarbanes-Oxley Act on the relation between corporate governance mechanisms and cost of debt for a sample of American firms. Our results show that the cost of debt is positively related to board size in the pre-SOX period. However, creditors become insensitive to board size, after SOX. We also find that the negative effect of board independence and institutional ownership on the cost of debt is more strongly in the post-SOX period relative to the pre-SOX period. This evidence demonstrates that the quality of control of these actors is improved following SOX. The positive effect of managerial ownership and duality on the cost of debt weakens after SOX highlighting a reduction of managerial power after 2002. Moreover, audit committee characteristics (size, meeting, independence and expertise) became after SOX effective mechanisms, for creditors, that enhance the quality of financial information and negatively affect the cost of debt. Finally, the results don’t show a significant relationship between the nomination and compensation committee exempt of CEO and cost of debt over the two periods of the study.