In the event of disputes between members of the World Trade Organization, the claimant member, based on Understanding on Rules and Procedures governing the Settlement of Disputes (DSU), should request Dispute Settlement Body (DSB) to make the respondent comply with rules and regulation. If the DSB decided that the breach of the rules has occurred, the breaching party must implement the DSB’s recommendations and decisions by promptly bringing its measures into conformity with the covered agreements. If prompt compliance is impracticable, it shall do so within a ‘reasonable period of time’. The DSU does not adopt criteria for determining the reasonable period and indeed, the ambiguous language of the DSU has led to confusion and conflicting decisions. Therefore, this article aims to examine how to determine this period by presenting a criterion that could help arbitrators decide. Due to numerous shortcomings in current rules and regulation, this article, first, illustrates problems raised and then consider proposals for the amendment.