The last fifteen years have recorded a proliferation of multi-jurisdictional competition law cases. Moreover, a number of bilateral agreements have been concluded between different National Competition Authorities (NCAs). However, the degree of bilateral cooperation between the NCAs of different developing countries is still quite limited. The article analyzes these issues taking Brazil and Argentina as case study. These countries have enforced a competition law since 1994 and 1999 respectively. However, while Brazil has improved the quality of its enforcement action during the last years, in Argentina little progress has been recorded. The NCAs of the two countries have adopted a number of initiatives at the Mercosur and bilateral level in order to increase the degree of coordination. Nevertheless, to date these initiatives have not been successful. This article argues that the lack of cooperation has been caused by the different stages of development of the competition law in the two countries, and due to the lack of personal contacts between the officers of the NCAs. In its conclusions the article identifies a number of lessons applicable to the NCAs of other developing countries which aim at strengthening their bilateral cooperation.