The 15 ECOWAS countries are now on track to implement the ECOWAS Common External Tariff by the end of the year 2007. Completion of the customs union is a key condition imposed by the European Union for negotiating an EU-West Africa Economic Partnership Agreement. This report analyzes the experience of the Common External Tariff of the UEMOA (Union Economique et Monétaire Ouest Africaine) . It is also a clear and synthetic panorama of this question.