EU Internal Market law and international arbitration increasingly interact with each other but there are important areas of conflict between the two that represent an obstacle to market integration in a common area of justice. The article examines, from the perspective of EU public economic law, these areas of conflict to assess the extent to which the Internal Market needs harmonised rules on commercial arbitration to support dispute resolution and access to an efficient delivery of justice within its operation. The current state of affairs is unsatisfactory and it lacks legal certainty. If properly regulated, commercial arbitration can become an important instrument functional to EU market efficiency.