Background: As a reform plan of health care system, Accountable Care Organization (ACO) has became an object of attention in the United States after Patient Protection and Affordable Care Act was enacted. ACO is a group of various health care providers and provide coordinated care to its assigned beneficiaries. If ACOs improve the quality level and reduce the cost of care, they can get financial incentives. Under the discussion for a quite long time and demonstration projects, ACO has been established. We aimed to analysis and discuss the history, policy mechanism, contents, status and outcomes of ACO. Also, we intended to suggest political implication Korean health care system with regard to ACO. Methods: We searched the articles related ACO in PubMed and selected several available papers about ACO. Total 56 studies were reviewed and categorized three parts; demonstration projects for formation of ACO, policy mechanism and agenda, empirical results of ACO performance. Results: As a result, establishment of ACO was successful partly in the US. It seems to be due to various project and pilot test for verification in the long time. The empirical effect of ACO was also identified in a few study but it needs more evidences to judge its positive effect. Conclusion: In Korea, there are arguments for the application of ACO. However it is difficult to implement a ACO by different political conditions between Korean and US. Nevertheless ACO proposed us the necessity of paradigm shift in our health policy and could be significant to national policy orientation in the future.