APEC``s open regionalism, modifying common perceptions of regional arrangements, suggests an open, non discriminatory posture toward non APEC countries. Given the size of the APEC member economies and the economic dynamism of the Asia Pacific region, this combination of integration and non exclusion has a significant potential impact to the general world trade system. Based on the open regionalism principle, APEC has played a central role in the successful conclusion of ITA and in the launch of UR and the New Round. Overall, APEC``s role as a vehicle for facilitating trade and regional cooperation has been balanced and meaningful. Recently, the regional economic environment in Asia is drastically changing. Economic development and apparent success of trading blocs in other regions, have forced many countries in Asia to consider establishing institutionalized frameworks in the region. East Asian countries started to negotiate regional trade agreements (RTAs) with neighboring economies. In this changing environment, APEC``s policies and activities, based on the principle of open regionalism, have a significant potential to contribute to the success of the liberal world trade order. It can effectively bridge the gap between the multilateralism of the GATT/WTO system and the powerful incentives to act on a regional basis. The open regionalism is, however, still open to full endorsement and continuous commitment from the APEC members. In order to obtain the endorsement and commitment, APEC has to produce concrete results in many agenda items with the update of the Osaka Action Agenda. By prioritizing issues and agenda, APEC should selectively tackle “sensitive issues” such as labor standards, agricultural subsidies and the misuse of anti dumping practices. Cooperation for financial stability and practical activities in information and telecommunications must also be increased. In the end, APEC should concretize the concept of open regionalism. A well designed and well implemented operational definition of open regionalism has potential to contribute to strengthening the multilateral trading system and to disciplining regional trading blocs which are WTO inconsistent. Only substantial accumulation of the practical progresses and well followed open regionalism will lead APEC to the position of powerful arbitrator between two formidable forces in theinternational trade system Mutilateralism and Regionalism.