As to the financial crises of the early twentieth century, followed by the emphasis on legal and professional bodies and the regulation related to the roles and responsibilities of the audit committee as well, especially the Sarbins-Oxley Law, we have witnessed extensive research on the effectiveness of the audit committee in parallel. These researches seem to be in lines with the requirements and regulations codified, including the SOX law and documenting the expectations of the audit committee. purpose of this study is to review the effectiveness of the audit committee and Post-SOX research through using previous research and library approach. The results indicate the positive effects of the audit committee on the quality of financial reporting, controls and internal auditing, the audit process and the positive reaction of the capital market. However, the results are inconclusive and sometimes contradictory in areas such as the compensation for committee members and non-financial expertise of them. These sections can be an appropriate bed for further research in the future. In general, it can be said that the evidence and the results of the studies support the effectiveness of the regulations related to the characteristics of the audit committee.